**原文标题**: 2020 USMSTF共识：结肠镜检查及息肉切除术后随访建议 --- Downloaded from http://journals.lww.com/ajg by BhDMf5ePHKbH4TTImqenVHwXmMsAVI5g3ImrOchK92T9UkdE9fcOoNIqE23yJzTYUbgDXZAbDjo= on 03/04/2020 Recommendations for Follow-Up After Colonoscopy and Polypectomy: A Consensus Update by the US Multi-Society Task Force on Colorectal Cancer Samir Gupta1,2,3, David Lieberman4, Joseph C. Anderson5,6,7, Carol A. Burke8, Jason A. Dominitz9,10, Tonya Kaltenbach11,12, Douglas J. Robertson5,6, Aasma Shaukat13,14, Sapna Syngal15,16 and Douglas K. Rex17 SUPPLEMENTARY MATERIAL accompanies this paper at http://links.lww.com/AJG/B394, http://links.lww.com/AJG/B395, http://links.lww.com/AJG/B396 Am J Gastroenterol 2020;115:415–434. https://doi.org/10.14309/ajg.0000000000000544 Colonoscopy is performed routinely for colorectal cancer (CRC) screening, follow-up of other abnormal screening tests, workup of signs and symptoms of gastrointestinal disease, and surveillance after CRC and polyp removal. Post procedure, colo- noscopists are expected to provide follow-up recommendations to patients and referring physicians. Recommendations for follow-up after normal colonoscopy among individuals age-eligible for screening, and post-polypectomy among all individuals with pol- yps are among the most common clinical scenarios requiring guidance.1 Risk of metachronous advanced neoplasia is associated with findings on prior colonoscopy. After high-quality colonoscopy, patients with no neoplasia detected are at the lowest risk, and those with polyps are risk-stratified based on the histology, number, lo- cation, and size of polyps detected. Since the release of the last US Multi-Society Task Force (Task Force) recommendations for post- colonoscopy follow-up and polyp surveillance in 2012,2 a number of articles have been published on risk of CRC based on colono- scopy findings and patient characteristics, as well as the potential impact of screening and surveillance colonoscopy on outcomes, such as incident CRC and polyps. Further, recent studies in- creasingly reflect the modern era of colonoscopy with more awareness of the importance of quality factors (eg, adequate bowel preparation, cecal intubation, adequate adenoma detection, and complete polyp resection), and utilization of state of the art tech- nologies (eg, high-definition colonoscopes). Higher-quality colo- noscopy could impact the importance of previously identified risk factors.Our aim was to review newly available evidence and update recommendations for follow-up after colonoscopy with or without polypectomy. METHODS Evidence Review and Recommendation Development To identify issues of greatest importance for the current revision, we developed PICO (patient, intervention, comparison, and outcome) questions (Supplementary Appendix A, http://links. lww.com/AJG/B394 [SG and DL, with input from TK]). In con- sultation with a certified medical librarian (KH), literature searches were performed in PubMed, Embase, and CINAHL with a combination of controlled vocabulary and keyword terms for colonoscopy, polyps, and polypectomy surveillance (see Supple- mentary Appendix B, http://links.lww.com/AJG/B395 for search terms). English-language articles since January 1, 2012 were re- trieved. Searches were run on March 30, 2017, and identified a total of 1904 unique articles (see Supplementary Appendix C, http://links.lww.com/AJG/B396 for article selection flow). Criteria used for inclusion/exclusion of titles, abstracts, and articles are outlined in Table 1. All titles were reviewed by a single author (SG) and potentially relevant titles were selected for Criteria for Inclusion/Exclusion of Titles, Abstracts, and Articles Review phase (reviewer) Inclusion/exclusion criteria Title (SG) Goal: Identify article(s) that might examine the relationship between baseline colonoscopy examination and subsequent neoplasia on follow-up Exclusion criteria • Title clearly not relevant • Review articles except other guidelines • Focus on high-risk conditions, such as inflammatory bowel disease, history of CRC, or hereditary CRC syndromes • Focus on children or more PICO questions • Examined relationship between baseline colonoscopy examination findings and detection of CRC or advanced adenoma on follow-up • Examined relationship between surveillance vs no surveillance for individuals who have undergone baseline polypectomy • Exclusion criteriaa • Methods insufficiently described to enable interpretation of study outcomes • Narrative review or editorial • Guidelines • Focus on high-risk conditions, such as inflammatory bowel disease, history of CRC, or hereditary CRC syndromes • Focus on children • or more of the following findings: • Adenoma $10 mm in size • Adenoma with tubulovillous/villous histology • Adenoma with high-grade dysplasia Advanced neoplasia 1 or more of the following findings: • Adenoma $10 mm in size • Adenoma with tubulovillous/villous histology • Adenoma with high-grade dysplasia • CRC High-risk adenoma 1 or more of the following findings: • Advanced neoplasia • 3 or more adenomas Adequate ADR ADR $30% in men and $20% in women Adequate bowel preparation Bowel preparation adequate for visualization of polyps .5 mm in size Complete examination Complete colonoscopy to cecum, with photo documentation of cecal landmarks, such as the appendiceal orifice, terminal ileum, or ileocecal valve High-quality examination Examination complete to cecum with adequate bowel preparation performed by colonoscopist with adequate adenoma detection rate and attention to complete polyp excision aWe propose moving forward that rather than using categories such as “high-risk adenoma” or “low-risk adenoma,” that research articles specify the individual criteria being captured by the category (eg, use 1–2 adenomas ,10 mm instead of the term low-risk adenoma) because evidence supporting level of risk for various criteria are constantly evolving. © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 417 adenoma. As part of the definition of villous or tubulovillous histology, we do not quantify the proportion of adenoma with villous features, as this is rarely reported in clinical practice. Also, criteria used to define villous histology are often not reported in studies and, when reported, are often variable. Patients with 3 or more adenomas (often discussed as “multiple adenomas”) have been reported previously to be at an increased risk of metachronous advanced neoplasia and, in many studies, considered as belonging to a high-risk predictor or outcome group. As such, to summarize prior evidence in this report, “high-risk adenoma” refers to patients with advanced neoplasia or $3 adenomas. We recognize variability across studies in the use of the term high-risk adenoma, with some using this term as a synonym for advanced neoplasia (Table 3). However, when possible, we will make a distinction between advanced neo- plasia and high-risk adenoma because implications of having any advanced neoplasia vs any high-risk adenoma (defined by advanced neoplasia and/or multiple adenomas) on risk for metachronous neoplasia may vary. We recognize that evidence on risks for metachronous neoplasia associated with SSPs and large HPs is evolving. For example, uncertainty exists as to whether HPs $10 mm in size represent lesions associated with increased risk. Because evidence of the risk of metachronous neoplasia associated with serrated lesions is evolving, whenever possible we have chosen not to include SSPs and HPs in our definitions of low-risk adenoma, high-risk adenoma, and ad- vanced neoplasia, and will refer to these lesions separately. We utilize specific findings (eg, 1–2 adenomas ,10 mm) rather than summary categories (low-risk adenoma) to be as precise as possible in our updated scenario-specific recommendations be- cause evidence supporting level of risk for various criteria are constantly evolving, and because prior terminology may be con- fusing (eg, use of high-risk adenoma to refer to both advanced neoplasiaand/orhaving3ormoreadenomas)andlimitpreciserisk stratification. All recommendations assume the colonoscopist has performed a high-quality examination (Table 3). Colonoscopy quality assumptions. For the purposes of this re- view, we have defined high quality based on colonoscopist per- formance, such as adequate adenoma detection rate (ADR), and examination-specific characteristics, such as examination com- plete to cecum, attention to complete polypectomy, and adequate bowel preparation to reliably detect lesions .5 mm. Benchmarks for ADR (ADR .30% in men; .20% in women), proportion of examinations with adequate preparation (.85%), and pro- portion of examinations complete to cecum (.95%) should be universally and routinely monitored as colonoscopy quality metrics in practice.7 Colonoscopists who are measuring quality metrics, but not meeting them, need to take steps to improve their examination quality and document this improvement. Polyp size is a major factor in our scenario-specific recommendations. Given the importance of polyp size for informing surveillance intervals, documentation of a polyp $10 mm within a report should be accompanied by an endoscopic photo of the polyp with comparison to an open snare or open biopsy forceps. Such doc- umentation is important for lesions such as HPs, where small size (,10 mm) is associated with well documented low risk for sub- sequent advanced neoplasia, but size $10 mm may be associated with elevated risk. We define complete polypectomy or complete removal as removal of all visually detected polypoid tissue (re- gardless of morphology). RESULTS Risk for Incident and Fatal Colorectal Cancer After Normal Colonoscopy and After Polyp Removal Normal colonoscopy is associated with sustained reduced risk for incident and fatal CRC. (High quality of evidence) A cohortstudy of 304,774 individualswith normal colonoscopy vs 980,154 individuals with no lower endoscopy showed a reduced risk for incident CRC on long-term follow-up (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.38–0.52). The risk was per- sistently decreased across a range of years since last normal colo- noscopy, ranging from an HR of 0.35 for #3 years to 0.65 at $15 years. Normal colonoscopy was also associated with reduced risk for fatal CRC (HR, 0.32; 95% CI, 0.24–0.45) over 300,000 person- years of follow-up.8 A cohort study comparing 131,349 individuals who had normal colonoscopy to the general population in Utah showed the standardized incidence ratio (SIR) for CRC was 0.26 (95% CI, 0.19–0.32) through 5 years and 0.60 (95% CI, 0.44–0.76) for7–10yearsoffollow-up.9A70%relativerisk(RR)reductionwas observed through the 10-year follow-up period (SIR, 0.28; 95% CI, 0.24–0.33). Most recently, a cohort study of 1,251,318 adults at average risk for CRC served by a large health plan in the United States reported a 46% relative reduced risk for incident and a 88% relativereduced riskfor fatal CRCamong99,166whohad anormal screeningcolonoscopythroughthetraditionallyrecommended10- year follow-up period for these individuals (HR, 0.54; 95% CI, 0.31–0.94 for incident and HR, 0.12; 95% CI, 0.02–0.82 for fatal CRC).10 Notably, reduced risk was noted even up to 12 years post–normal screening colonoscopy. A strength of this study was the use of a validated approach to identifying screening colono- scopy procedures. A potential limitation was unmeasured differ- ences between plan members who elected screening colonoscopy vs stool-based testing or sigmoidoscopy, including a potential healthy user bias. A modeling study, informed by age-specific rates of adenoma, advanced adenoma, and CRC observed among 4.3 million individuals who underwent screening colonoscopy, sug- gested that a normal colonoscopy was associated with a ,0.5% 10- year risk of subsequent CRC.11 Since the 2012 review, we could identify no new data on risk of advanced neoplasia associated with small rectosigmoid HPs. Earlier literature has suggested that such patients have a risk of metachronous advanced neoplasia similar to that of patients with a normal examination, and recommendations for 10-year repeat examination remain unchanged.2 Incremental effectiveness of repeat colonoscopy after baseline normal colonoscopy for further reducing CRC incidence and mortality is uncertain. (Insufficient evidence) While we found no direct evidence to support the incremental effectiveness of repeat colonoscopy after 10 years, prior modeling studies have suggested that repeat colonoscopy in those with a baseline normal examination does confer additional benefit.12–14 Knudsen et al14 estimated that rescreening after initial normal colonoscopy resulted in a reduction from 31.3 lifetime CRC cases per 1000 persons with no further screening to as low as 7.7 cases per 1000 persons with repeat screening. Based on current avail- able evidence, our recommendation for repeat colonoscopy 10 years after a normal colonoscopy remains unchanged. Risk for incident and fatal CRC after baseline adenoma removal is uncertain. (Low quality of evidence) Four recent studies have shown that individuals with ade- noma, despite adenoma removal, may have increased risk for CRC compared to the general population. An Irish cohort study The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 418 of 6972 patients with adenomas identified between 2000 and 2005 found a 2.9-fold increased risk for incident CRC compared to the general population (SIR, 2.85; 95% CI, 2.61–3.25).15 An- nual reported risk of CRC was 0.43% per year, and cumulative rate of CRC was ,5% for men, and ,3.5% for women with up to 10 years follow-up. This study was limited by lack of in- formation on polyp size in the registry, limited information on type of follow-up patients received, and incomplete colono- scopy at baseline in some individuals. A French cohort study of 5779 patients diagnosed with any adenoma 1990–1999 followed through 2003 found risk of CRC increased 1.3-fold after first adenoma removal compared to the general population (SIR, 1.26; 95% CI, 1.01–1.56).16 Stratifying based on adenoma risk category (advanced adenoma and nonadvanced adenoma) showed baseline advanced adenoma was associated with a 2.2- fold increased CRC risk compared to the general population (SIR, 2.23; 95% CI, 1.67–2.92), while baseline nonadvanced adenoma was associated with reduced CRC risk (SIR, 0.68; 95% CI, 0.44–0.99). The 10-year cumulative probability of CRC in patients with advanced adenomas was 2.05% (95% CI, 1.14%–3.64%) with and 6.22% (95% CI, 4.26%–9.02%) without exposure to subsequent surveillance colonoscopy. A Norwegian cohort study of 40,826 patients with adenomas removed during years 1993–2007 and followed through 2011 found risk for fatal CRC was similar compared to the general population.17 Risk was decreased by 25% for those with low-risk adenoma (defined by single adenoma without advanced histology; standardized mortality ratio, 0.75; 95% CI, 0.63–0.88], but increased 1.2-fold for those with high-risk adenoma (defined by $2 adenomas, villous histology, or high-grade dysplasia; standardized mor- tality ratio, 1.16; 95% CI, 1.02–1.31). A limitation of this analysis was the inability to account for polyp size in the definition of high-risk adenoma. Among 15,935 participants in a US trial of sigmoidoscopy screening who completed subsequent colono- scopy, compared to those with no adenoma, the risk for incident and fatal CRC was increased among participants with advanced adenoma (RR, 2.7; 95% CI, 1.9–3.7 for incident; RR, 2.6; 95% CI, 1.2–5.7 for fatal), but similar among participants with non- advanced adenoma (RR, 1.2; 95% CI, 0.8–1.7 for incident CRC and RR, 1.2; 95% CI, 0.5–2.7 for fatal CRC).18 Notably, 11.3% of the nonadvanced adenoma group had 3 or more adenomas, while 88.7% had 1–2 adenomas; none had villous features or high-grade dysplasia, and all were ,10 mm. At median of 12.9 years follow-up, cumulative CRC incidence was 2.9% for the advanced adenoma group, 1.4% for the nonadvanced adenoma group, and 1.2% in the no adenoma group. Caution is warranted in interpreting the incident CRC outcomes for the nonadvanced vs no adenoma groups, as the nonadvanced group had greater exposure to subsequent colonoscopy follow-up, perhaps in- troducing detection bias; cumulative colonoscopy exposure af- ter baseline examination was 53.0% vs 36.9% at 5 years and 78.1% vs 69.9% at 9 years follow-up for the nonadvanced vs no adenoma groups, respectively. Surveillance colonoscopy after baseline removal of ade- noma with high-risk features (eg, size ‡10 mm) may reduce risk for incident CRC, but impact on fatal CRC is uncertain. (Low quality of evidence) Incremental impact of surveillance colonoscopy after baseline removal of adenoma with low-risk features (such as 1–2 adenomas <10 mm) on risk for incident and fatal CRC is uncertain. (Low quality of evidence) Little prior research has examined the incremental benefit of surveillance (compared to no surveillance) colonoscopy on CRC risk after baseline polypectomy. Since the last review, 2 studies provided some evidence that surveillance may reduce CRC risk. A cohort study of 11,944 patients with intermediate-risk adenoma compared risk for incident CRC among patients exposed vs un- exposed to surveillance colonoscopy, as well as for the entire group compared to the general UK population.19 Intermediate risk was based on UK polyp risk stratification guidelines, defined as having 1–2 adenomas $10 mm or 3–4 adenomas ,10 mm in size; both of these groups would have been classified as high risk per 2012 Task Force guidelines. At median of 7.9 years follow-up, 42% did not receive surveillance colonoscopy. Exposure to 1 or 2 surveillance examinations was associated with a 43%–48% rela- tive reduction in incident CRC risk (adjusted HR, 0.57 for 1 ex- amination; 95% CI, 0.40–0.80 and HR, 0.52 for 2 examinations; 95% CI, 0.31–0.84). Risk for incident CRC was independently associated with increasing age, adenoma $20 mm in size, ade- noma with high-grade dysplasia, proximal adenoma, incomplete baseline examination, and poor bowel preparation. The absolute risk for incident CRC was 2.3% with vs 2.7% without 1 surveil- lance examination. In a higher-risk group defined by having in- complete colonoscopy, poor preparation, high-grade dysplasia, proximal adenoma, or adenoma $20 mm, the absolute rate of incident CRC was 2.8% with vs 3.3% without a surveillance ex- amination, corresponding to a statistically significant reduced CRC risk for exposure to surveillance for this higher-risk group (HR, 0.52; 95% CI, 0.36–0.75). Among individuals not meeting the criteria for the higher-risk group, the absolute rate of incident CRC among individuals exposed vs unexposed to at least 1 sur- veillance examination was 0.7% vs 1.1%, and associated with a nonstatistically significant reduced CRC risk (HR, 0.54; 95% CI, 0.20–1.43). Limitations of this study are that only patients with intermediate-risk adenomas were included, and that mortality was not assessed. In summary, this study demonstrates that surveillance colonoscopy, within a group of patients with 1–2 adenomas $10 mm or 3–4 adenomas ,10 mm in size may re- duce risk for incident CRC, particularly among those with base- line incomplete colonoscopy, poor preparation, high-grade dysplasia, adenoma $20 mm, and/or proximal adenoma. In patients without these findings, exposure to surveillance afforded no statistically significant observed reduction in risk for incident CRC. The previously mentioned French cohort study of 5779 patients with adenoma also reported on the impact of exposure to surveillance. Exposure to follow-up colonoscopy had a marked effect on risk of CRC, especially in patients with an advanced adenoma. The risk fell to that found within the general population if patients with an advanced adenoma had at least 1 follow-up colonoscopy (SIR, 1.10; 95% CI, 0.62–1.82), while this risk was more than 4 times higher in patients without follow-up colono- scopy (SIR, 4.26; 95% CI, 2.89–6.04).16 Taken together, new evidence suggests that adenoma-bearing patients with identifiable high-risk characteristics remain at in- creased risk for CRC in the absence of surveillance,17 and that exposure to surveillance is associated with reduced risk for some high-risk groups defined by baseline low quality of examination or polyp characteristics. Further, new evidence suggests that most adenoma patients (such as those with 1–2 small adenomas) are at lower than average risk for subsequent CRC than the general population after baseline polypectomy. The incremental benefit of subsequent surveillance is uncertain for all patients with © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 419 polyps, but benefit among patients with higher-risk features (size $20 mm) is suggested by 2 studies. These studies highlight the importance of additional research to identify patients most likely to benefit from surveillance, and careful clinical management pending further clarification of which patients are at highest risk, and which strategies will be most effective for reducing risk. Limitations of prior studies include retrospective nature and subsequent inability to control for confounding factors that could be associated with CRC risk and likelihood of participation in surveillance, such as proclivity toward healthy behaviors and following medical recommendations for follow-up. Risk for incident and fatal CRC among individuals with baseline SSP is uncertain. (Very low quality of evidence) In a Danish case-control study of 2045 CRC cases compared to 8105 CRC-free controls nested within a cohort of individuals who received colonoscopy between 1977 and 2009, having an SSP was associated with 3-fold increased odds for CRC (odds ratio [OR], 3.07; 95% CI, 2.30–4.10), while having SSP with dysplasia was associated with a nearly 5-fold increased odds for CRC (OR, 4.76; 95% CI, 2.59–8.73) compared to having no polyp.20 A limitation of this study is that it is unclear whether baseline polyps were excised or only biopsied because all SSP patients were identified based on pathology records, but colonoscopy records were not reviewed. A cohort study of patients included in a sigmoidoscopy screening trial compared CRC risk among 81 patients with $10 mm serrated lesions (including an SSP, TSA, HP, or un- classified serrated lesions) to risk among patients who had a nonadvanced adenoma, normal sigmoidoscopy, or no screen- ing.21 Compared to the group with no screening, a 2.5-fold nonstatistically significant increased risk for incident CRC was observed in individuals with large serrated polyps (HR, 2.5; 95% CI, 0.8–7.8). Compared to the normal sigmoidoscopy group, a 4- fold increased risk for incident CRC was observed in individuals with large serrated polyps (HR, 4.2; 95% CI, 1.3–13.3). Risk for incident CRC for individuals with advanced adenoma at baseline compared to those with no screening was increased 2-fold (HR, 2.0; 95% CI, 1.3–2.9). On multivariable analyses adjusted for histology, size, and number of concomitant adenomas, having a large serrated polyp was associated with a 3.3-fold increased risk for incident CRC (OR, 3.3; 95% CI, 1.3–8.6). Interestingly, very little progression (including no progression to cancer) was ob- served in 23 large serrated polyps left in situ for a median 11 years of follow-up, suggesting that some serrated polyps may be a general biomarker of risk rather than an intermediate high-risk lesion. This study is limited by the small sample size, and un- certainty regarding whether a group of patients ascertained as a result of a sigmoidoscopy trial are representative of patients routinely encountered with SSP at colonoscopy. Despite data suggesting that patients with SSP have increased risk for CRC, the magnitude and significance of risk associated with SSPs is un- certain, given limitations of available studies. Summary of risk for incident and fatal CRC after normal colonoscopy and after polyp removal. Studies published since our last recommendations suggest the evidence to support a low risk for incident and fatal CRC after normal screening colono- scopy is stronger. There continues to be little evidence on the incremental effectiveness of a repeat screening colonoscopy at 10 years after normal colonoscopy, but modeling studies suggest benefit. Recent studies vary in estimates of risk for incident and fatal CRC after baseline adenoma removal, with some showing increased risk, and others showing decreased risk. New evidence suggests that exposure to surveillance colonoscopy after baseline adenoma removal may reduce CRC risk, but the magnitude of benefit associated with exposure to surveillance colonoscopy is unclear. Generally, individuals with more advanced findings at baseline (or colonoscopy with poor baseline quality) have higher risk for subsequent cancer relative to those with low-risk findings (eg, 1–2 small adenomas) and benefit of repeat surveillance colonoscopy is more demonstrable in the higher-risk groups. Further, determining which groups are most likely to benefit, and whether surveillance reduces CRC mortality, remains a challenge. Recent studies suggest patients with SSPs may have an increased risk for incident CRC, but magnitude and consistency of risk remains uncertain. Overall, more evidence is needed to un- derstand which patients are at lowest and highest risk for incident and fatal CRC after initial colonoscopy, and whether surveillance can consistently improve outcomes. Nonetheless, pending gen- eration of new evidence, we provide colonoscopy surveillance recommendations to guide patient care, given the prevailing conventional wisdom and available observational evidence sug- gesting that some patients remain at risk for CRC despite baseline polypectomy. Recommended Post-Colonoscopy Surveillance Strategies for Reducing Colorectal Cancer Risk For patients with normal, high-quality colonoscopy, repeat CRC screening in 10 years. (Strong recommendation, high quality of evidence) New observational and modeling studies of colonoscopy confirm and strengthen the evidence base to support the conclusion that individuals with normal colonoscopy are at lower than average risk for CRC, as mentioned previously.8–11 Based on this reduced risk, we recommend CRC screening in average-risk individuals be repeated 10 years after a normal examination complete to the cecum with bowel preparation adequate to detect polyps .5 mm in size. Future studies may clarify whether lengthening the interval beyond 10 years may be possible. A 10-year follow-up after normal colonoscopy is recommended regardless of indication for the colonoscopy, except for individuals at increased risk for CRC, such as those with history of a hereditary CRC syndrome, personal history of inflammatory bowel disease, personal history of hereditary cancer syndrome, serrated polyposis syndrome, malignant polyp, personal history of CRC, or family history of CRC (Tables 4 and 5; Figure 1). For patients with 1–2 tubular adenomas <10 mm in size completely removed at a high-quality examination, repeat colonoscopy in 7–10 years. (Strong recommendation, moderate quality of evidence) The Task Force previously recommended repeat colonoscopy withina rangeof 5–10 years for individuals with 1–2 small tubular adenomas. The shift in recommendation to a longer interval is based on new studies that confirm and extend prior evidence to suggest that individuals with low-risk adenomas have reduced risk for advanced neoplasia, as well as incident CRC on follow-up. Since our last review, 2 meta-analyses examining risk for meta- chronous advanced neoplasia among patients with low-risk ad- enomas have been published. The first pooled data from 11,387 individuals across 7 studies reported between 1992 and 2013 with 2–5 years follow-up after baseline colonoscopy. The pooled rate of metachronous advanced neoplasia was 3.6% for individuals with baseline low-risk adenoma and 1.6% for those with normal The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 420 Table 4 US Multi-Society Task Force Recommendations for Post-Colonoscopy Follow-Up in Average-Risk Adults With Normal Colonoscopy or Adenomasa Baseline colonoscopy finding Recommended interval for surveillance colonoscopy Strength of recommendation Quality of evidence Normal 10 yb Strong High 1–2 tubular adenomas ,10 mm 7–10 yc Strong Moderate 3–4 tubular adenomas ,10 mm 3–5 y Weak Very low 5–10 tubular adenomas ,10 mm 3 y Strong Moderate Adenoma $10 mm 3 y Strong High Adenoma with tubulovillous or villous histology 3 yd Strong Moderate Adenoma with high-grade dysplasia 3 yd Strong Moderate .10 adenomas on single examinatione 1 y Weak Very low Piecemeal resection of adenoma $20 mm 6 mo Strong Moderatef aAll recommendations assume examination complete to cecum with bowel preparation adequate to detect lesions .5 mm in size; recommendations do not apply to individuals with a hereditary CRC syndrome, personal history of inflammatory bowel disease, personal history of hereditary cancer syndrome, serrated polyposis syndrome, malignant polyp, personal history of CRC, or family history of CRC, and must be judiciously applied to such individuals, favoring the shortest indicated interval based on either history or polyp findings. bFollow-up may be with colonoscopy or other screening modality for average-risk individuals. cPatients with recommendations issued before 2020 for shorter than 7- to 10-year follow-up after diagnosis of 1–2 tubular adenomas may follow original recommendations. If feasible, physicians may re-evaluate patients previously recommended an interval shorter than 10 y and reasonably choose to provide an updated recommendation for 7- to 10-year follow-up, taking into account factors such as quality of baseline examination, polyp history, and patient preferences. dAssumes high confidence of complete resection. ePatients with .10 adenomas or lifetime .10 cumulative adenomas may need to be considered for genetic testing based on absolute/cumulative adenoma number, patient age, and other factors such as family history of CRC (see text). fSee US Multi-Society Task Force recommendations for endoscopic removal of colorectal lesions.69 Table 5 US Multi-Society Task Force Recommendations for Post-Colonoscopy Follow-Up in Average-Risk Adults With Serrated Polypsa Baseline colonoscopy finding Recommended interval for surveillance colonoscopy Strength of recommendation Quality of evidence #20 HPs in rectum or sigmoid colon ,10 mmf 10 yb Strong Moderate #20 HPs proximal to sigmoid colon ,10 mmf 10 y Weak Very low 1–2 SSPs ,10 mm 5–10 y Weak Very low 3–4 SSPs ,10 mm 3–5 y Weak Very low 5–10 SSPs ,10 mm 3 y Weak Very low SSP $10 mm 3 y Weak Very low SSP with dysplasiae 3 y Weak Very low HP $10 mm 3–5 yc Weak Very low TSA 3 y Weak Very low Piecemeal resection of SSP $20 mm 6 mo Strong Moderated aAll recommendations assume examination complete to cecum with bowel preparation adequate to detect lesions .5 mm in size; recommendations do not apply to individuals with a hereditary CRC syndrome, personal history of inflammatory bowel disease, personal history of hereditary cancer syndrome, serrated polyposis syndrome, or malignant polyp, personal history of CRC, or family history of CRC, and must be judiciously applied to individuals with a personal or family history of CRC, favoring the shortest indicated interval based on either history or polyp findings. bFollow-up may be with colonoscopy or other screening modality for average risk individuals. cA 3-year follow-up interval is favored if concern about consistency in distinction between SSP and HP locally, bowel preparation, or complete excision, whereas a 5-year interval is favored if low concerns for consistency in distinction between SSP and HP locally, adequate bowel preparation, and confident complete excision. dSee US Multi-Society Task Force recommendations for endoscopic removal of colorectal lesions.69 eAssumes high confidence of complete resection. fPatients with cumulative .20 hyperplastic polyps distributed throughout the colon, with at least 5 being proximal to the rectum, as well as those with 5 serrated polyps proximal to the rectum . 5 mm, with at least two $ 10 mm meet criteria for serrated polyposis syndrome and may require specialized management.112 © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 421 colonoscopy (RR, 1.8; 95% CI, 1.3–2.6).22 The most recent meta- analysis pooled data from 10,139 individuals across 8 studies reported between 2006 and 2015 with 3–10 years of follow-up after baseline colonoscopy (Figure 2).23 Five-year cumulative in- cidence of metachronous advanced adenoma on follow-up was 4.9% for the low-risk adenoma group (95% CI, 3.18%–6.97%) and 3.3% for the no adenoma group (95% CI, 1.85%–5.10%; RR, 1.55; 95% CI, 1.24–1.94). In contrast, the same meta-analysis reported the 5-year cumulative incidence of metachronous advanced ad- enoma on follow-up was 17.1% (95% CI, 11.97%–23.0%) for individuals with advanced adenoma. Limitations of both of these meta-analyses include short duration of follow-up, as well as inclusion of many patients from randomized trials of inter- ventions to reduce polyp recurrence. Nonetheless, both meta- analyses suggest that the rate of metachronous advanced neo- plasia is low among individuals with 1–2 adenomas ,10 mm, and only marginally higher (no more than 2%) than the rate observed in people with normal colonoscopy at baseline. These studies are complemented by the aforementioned Norwegian cohort study, which found that the long-term risk of fatal CRC for 36,296 patients with a single adenoma without advanced histology (not taking into account size) was 25% lower than the general pop- ulation (standardized mortality ratio, 0.75; 95% CI, 0.63–0.88)17 and the previously cited French cohort study, which reported baseline nonadvanced adenoma was associated with reduced CRC risk compared to the general population (SIR, 0.68; 95% CI, 0.44–0.99).16 The French cohort study also noted no statistically significant difference in risk for incident cancer compared to the general population among patients exposed to surveillance colonoscopy after removal of 1–2 adenomas ,10 mm (SIR, 0.60; 95% CI, 0.30–1.07), although the point estimate for risk was higher among patients unexposed to surveillance (SIR, 0.82; 95% CI, 0.41–1.47).16 The previously mentioned US cohort study found cumulative CRC incidence at up to 15 years follow-up was 1.4% for individuals with nonadvanced adenoma vs 1.2% for individuals with no adenoma, and reported no difference in the rate of fatal CRC.18 A limitation of this study was inability to account for impact of exposure to surveillance colonoscopy, Figure 1. Recommendations for follow-up after colonoscopy and polypectomy. Recommendations for post-colonoscopy follow-up in average risk adults are depicted. After high-quality colonoscopy defined by examination complete to cecum adequate to detect polyps .5 mm, performed by a colonoscopist with adequate ADR with complete polyp resection, risk-stratified repeat colonoscopy intervals are provided. SSP, sessile serrated polyp/sessile serrated adenoma/sessile serrated lesion. Figure 2. Risk for metachronous advanced neoplasia among individuals with normal colonoscopy, 1–2 adenomas ,10 mm in size, or high-risk adenoma (adenoma .10 mm in size, adenoma with tubulovillous/villous histology, adenoma with high-grade dysplasia or $3 adenomas ,10 mm) based on a meta-analysis of 10,139 across 8 surveillance studies is depicted.23 Risk for metachronous adenoma among individuals with no adenoma or 1–2 small adenomas is similar, and much lower than risk amongindividuals with baseline high-risk adenoma. In studies that defined high risk as advanced adenoma alone (n 5 4 studies), cumulative ad- vanced adenoma risk was 16% (95% CI, 9%–25%), and in studies that defined high risk as advanced adenoma or $3 adenomas ,10 mm (n 5 4 studies), cumulative advanced adenoma risk was 19% (95% CI, 10%–30%; C Dube, personal communication, September 18, 2018). The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 422 which occurred among 78.7% of nonadvanced adenoma and 69.9% of no adenoma patients at up to 9 years follow-up in the subset of 3492 individuals from whom follow-up colonoscopy data were collected and presented. Thus, it is possible that ex- posure to surveillance colonoscopy contributed to the lack of difference in incident CRC observed between the nonadvanced adenoma and colonoscopy groups. We specifically searched for articles evaluating factors that might increase risk among individuals with 1–2 adenomas ,10 mm. In a pooled analysis of individuals with 1–2 small ad- enomas in 7 prospective polyp surveillance studies, an increased risk for metachronous advanced neoplasia was found for those with a history of polyps (absolute risk, 11.5%) or concurrent distal and proximal small adenomas (absolute risk, 11.0%).24 However, most studies contributing to this pooled analysis were random- ized trials of strategies to reduce polyp recurrence, and were performed before the era of modern colonoscopy, impacting relevance to current practice in which baseline adenoma de- tection may have improved due to focus on optimizing bowel preparation and ADRs. In a separate study that included an analysis of 4496 patients with 1–2 nonadvanced adenomas, risk for incident CRC was similar among those with proximal only vs distal only adenomas (RR, 1.5; 95% CI, 0.7–2.8).18 More research is needed to determine whether subsets of individuals with low- risk adenoma, such as those with advanced age, young-onset adenoma, proximal adenoma, male sex, or other factors might benefit from shorter duration of follow-up. We considered a recommendation of 10 years alone rather than a range of 7- to 10-year follow-up after removal of 1–2 adenomas ,10 mm in size, given that evidence supports that these patients are at lower than average risk for CRC. The 7- to 10-year range was chosen because of ongoing uncertainty regarding whether the observed lower than average risk for CRC could be reduced further by exposure to surveillance,17 and also because we cannot rule out the possibility that exposure to surveillance colonoscopy in some studies contributed to the low risk of CRC observed in these patients.16,18 We anticipate that ongoing work may clarify whether surveillance colonoscopy can improve outcomes in patients with 1–2 small adenomas, and also whether characteristics (such as size ,6 mm) may help guide the choice between recommending a shorter 7-year vs a longer 10-year surveillance interval. The Task Force recognizes that many patients with 1–2 nonadvanced adenomas ,10 mm will have had a prior docu- mented recommendation for a 5-year examination or other interval shorter than 7–10 years, consistent with 2012 recom- mendations. Patients with recommendations before this pub- lication for shorter than 7- to 10-year follow-up after diagnosis of 1–2 tubular adenomas ,10 years can reasonably follow original recommendations. Based on the new evidence pre- sented and our current recommendation for 7- to 10-year follow-up, if feasible, we suggest that physicians may re-evaluate patients previously recommended an interval shorter than 7–10 years and reasonably choose to provide an updated recom- mendation for follow-up between 7 and 10 years after the prior examination that diagnosed 1–2 adenomas ,10 mm, taking into account factors such as quality of baseline examination, polyp history, and patient preferences. For patients with 3–4 tubular adenomas ,10 mm in size completely removed at a high-quality examination, repeat colonoscopy in 3–5 years. (Weak recommendation, very low quality of evidence) For patients with 5–10 tubular adenomas ,10 mm in size completely removed at a high-quality examination, repeat colonoscopy in 3 years. (Strong recommendation, moderate quality of evidence) Since the 2012 recommendations, a number of studies have been published that included evaluation of risk among patients with 3–10 adenomas. These studies are consistent in demon- strating that individuals with 3–10 adenomas are at increased risk for advanced neoplasia25–30 and even CRC alone26,31 on follow-up. However, we were specifically interested in whether there was sufficient evidence to support longer surveillance intervals for patients with 3–4 small (,10 mm) adenomas. Our rationale for seeking such data is based on a postulate that the number of small adenomas found per patient may be increasing over time with greater attention to colonoscopy quality and use of high-definition colonoscopes.32 Several relevant studies were identified. In interpreting these studies, we considered the ob- servation from the previously mentioned meta-analysis, which found 5-year cumulative risk of metachronous neoplasia was 3.3% for the no adenoma and 4.9% for the 1–2 ,10-mm ade- noma group.23 A cohort study of 561 individuals with 3–4 ad- enomas ,10 mm suggested that the risk for metachronous advanced neoplasia among individuals with 3–4 adenomas was ,5%.33 This study was limited by the absence of a comparison group with only 1–2 nonadvanced adenomas. In a cohort study of 443 individuals with 1–9 adenomas ,10 mm, no group with ,10-mm polyps (including those with between 5 and 9 ade- nomas) had a rate of metachronous advanced neoplasia .10% on follow-up that extended up to 32 months.34 A limitation of this study was small sample size, particularly for subgroup analyses by number and size of polyps, and that data on the subgroup of patients with 3–4 adenomas were not reported. A single-center retrospective study of 1414 patients cared for at a large academic gastroenterology practice between 2002 and 2012 with high awareness of colonoscopy quality strategies found 5% of patients with 5 or more adenomas ,10 mm at baseline had metachronous advanced neoplasia on follow-up colonoscopy more than 200 days after baseline.35 Metachronous advanced neoplasia was found in just 1.8% of patients with 3–4 small adenomas at baseline, and 1.4% of those with 1–2 small adenomas. In comparison, the rate of metachronous advanced neoplasia was 16.3% for individuals with 5 or more adenomas with 1 $10 mm, and 8.6% for those with 3–4 adenomas with 1 $10 mm in size. As such, this study suggests that individuals with 1–2 low-risk adenomas, as well as those with 3–4 ,10-mm adenomas, at baseline might have a similar very low risk for metachronous advanced neoplasia in settings that include high attention to colonoscopy quality. In a cohort study that com- pared 572 patients with 3 or more nonadvanced adenomas to 4496 patients with 1–2 nonadvanced adenomas, no difference in risk for incident CRC was observed (RR, 1.01; 95% CI, 0.4–2.4), and the cumulative rate of advanced adenoma removal through up to 9 years of follow-up was similar: 10.7% for individuals with 3 or more nonadvanced adenomas vs 7.1% for individuals with 1–2 nonadvanced adenomas.18 Outcomes stratified by exact number of adenomas in the 3 or more nonadvanced adenoma group were not reported. Based on these studies, the Task Force suggests 3- to 5-year repeat colonoscopy for individuals with 3–4 adenomas ,10 mm in size, and favors a 5-year interval based on current evidence. However, the Task Force recognizes very low quality of evidence © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 423 to support the 3- to 5-year follow-up recommendation. More research is needed to determine if, in the modern era of colono- scopy, the risk for metachronous advanced neoplasia in indi- viduals with 3–4 tubular adenomas ,10 mm is low enough to permit a firm 5-year or even longer than 5-year interval to sur- veillance colonoscopy. Given limited available data to assess risk, the Task Force recommends 3-year repeat colonoscopy for indi- viduals with 5–10 adenomas ,10 mm in size. Future research may elucidate whether some individuals within this group (particularly those with 5–10 diminutive adenomas ,6 mm in size) may have low risk also warranting longer follow-up intervals. The Task Force recommends that the number of small adenomas at a given ex- amination should be considered in context of the cumulative number of lifetime adenomas, as differential management may be warrantedbased on having .10adenomas,as is highlightedbelow. For patients with 1 or more adenomas ‡10 mm in size completely removed at high-quality examination, repeat colonoscopy in 3 years. (Strong recommendation, high quality of evidence) Since the 2012 recommendations, additional studies have confirmed and extended the evidence supporting identification of 1or moreadenomas $10 mmsize as a high-risk feature.25–27,30,31A study of 2990 patients from the Netherlands diagnosed with ad- enoma 1988–2002 and followed through 2008 found size $10 mm was independently associated with 1.7-fold increased risk for metachronous advanced neoplasia (OR, 1.7; 95% CI, 1.2–2.3).30 A cohort study of 3300 patients diagnosed with ade- nomas at a large integrated US health care system found that size $10 mm was independently associated with 3.6-fold increased risk for advanced adenoma (OR, 3.6; 95% CI, 2.8–4.5) and 5.2- fold increased risk for CRC on follow-up (OR, 5.2; 95% CI, 1.8–15.1).26 An Australian cohort study of 5141 patients found having advanced neoplasia (defined as villous histology, size .9 mm, serrated histology, high-grade dysplasia, or .2 adeno- mas) was associated with increased risk for advancedneoplasia on follow-up, but risk associated with size .9 mm, villous histology, or high-grade dysplasia alone was not specifically examined. An additional limitation of this study was that half of the enrolled patients had a family history of CRC.27 As mentioned previously, a US cohort study found individuals with advanced adenoma had an increased risk for incident and fatal CRC compared to those with no adenoma, and the cumulative rate of advanced adenoma removal at up to 9 years follow-up was 13.0%.18 Although the study did not specifically report outcomes for individuals with adenoma $10 mm or larger, adenoma with high-grade dysplasia, or villous histology, the majority of individuals followed in the advanced adenoma group met the increased size criteria. As such, this study also supports closer follow-up for individuals with adenoma $10 mm. The Task Force acknowledges the impor- tance of accurate polyp size estimation for this recommendation and suggests photodocumentation verifying polyp size $10 mm relative to an open forceps or open snare of known size. For patients with adenoma containing villous histology completely removed at high-quality examination, repeat colonoscopy in 3 years. (Strong recommendation, moderate quality of evidence) Studies published since the 2012 recommendations continue to support villous histology as a potential risk factor for advanced neoplasia on follow-up. These studies include the aforemen- tioned 2 large cohort studies from a large US health care system and the Netherlands.26,27,30 For patients with adenoma containing high-grade dysplasia completely removed at high-quality examination, repeat colonoscopy in 3 years. (Strong recommendation, moderate quality of evidence) ThepreviouslycitedcohortstudyfromtheUnitedStates,aswell as 1 additional cohort study, have confirmed and extended evi- dence to support high-grade dysplasia as a risk factor for meta- chronous advanced neoplasia26,27,36 and CRC.26 However, the Netherlands cohort of 2990 patients did not find baseline high- grade dysplasia to be an independent predictor of risk.30 Studying high-grade dysplasia as a risk factor is a major challenge because this finding is rare at baseline, perhaps accounting for some of the variability in risk observed across studies. The 3-year recommen- dation assumes that there was complete resection of neoplasia, including high-grade dysplasia at the baseline examination. For patients with >10 adenomas completely removed at high-quality examination, repeat colonoscopy in 1 year. (Weak recommendation, very low quality of evidence) Since2012,wefoundasinglecohortstudyof214Koreanpatients with .10 adenomas in which risk for metachronous advanced ad- enoma was evaluated. At a median 4.3 years of follow-up, 26.6% had metachronous advanced adenoma.37 Patients with .10 adenomas may be at increased risk for having a hereditary polyposis syndrome, such as familial adenomatous polyposis or MYH-associated poly- posis,38 and multiple groups have recommended patients with .10 cumulative lifetime adenomas be considered for genetic testing.39,40 Decision to perform genetic testing may be based on absolute or cumulative adenoma number, patient age, as well as other factors, such as family history of CRC and/or personal history of features associated with polyposis, such as desmoid tumor, hepatoblastoma, cribriformmorularvariantofpapillarythyroidcancer,ormultifocal/ bilateral congenital hypertrophy of the retinal pigment epithelium.40 For patients with £20 HPs <10 mm in size in the rectum or sigmoid colon removed at a high-quality examination, repeat CRC screening in 10 years. (Strong recommendation, moderate quality of evidence) For patients with £20 HPs <10 mm in size proximal to the sigmoid colon removed at a high-quality examination, repeat colonoscopy in 10 years. (Weak recommendation, very low quality of evidence) Since the 2012 review, we could identify no new data on risk of advanced neoplasia associated with small rectosigmoid HPs. Prior literature has suggested that such patients have a similar risk of metachronous advanced neoplasia as patients with a normal examination, and recommendations for 10-year repeat exami- nation remain unchanged,2 although previous studies have been limited by either small sample size or evaluating patients who had both conventional adenoma and distal HPs at baseline. We spe- cifically searched for data to guide recommendations for patients with HPs ,10 mm proximal to the sigmoid colon. We found no published studies on the risk for metachronous advanced neo- plasia or large serrated polyps among patients with isolated HPs ,10 mm proximal to the sigmoid colon without synchronous conventional adenoma. We do note that in a cohort study of patients with serrated polyps, among 698 patients with HPs and no concurrent conventional adenomas, the proportion with high- risk adenoma at follow-up was 3.7% (26 of 698), and large ser- rated polyp (defined as HP or SSP $10 mm) was 1.6% (11 of 698), supporting the concept that most individuals with isolated HPs are a low-risk group; data on outcomes stratified by size and location of baseline HPs were not provided.41 We do recognize The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 424 concerns that in usual practice some SSPs may be misdiagnosed as HPs.42–47 If concerns regarding the ability of the local pathol- ogist to distinguish between SSP and HPs exist, some clinicians may choose to follow the recommendations for patients with SSPs provided below for patients identified with isolated proximal HPs ,10 mm. For patients with 1–2 SSPs ,10 mm in size completely removed at high-quality examination, repeat colonoscopy in 5–10 years. (Weak recommendation, very low quality evidence) We found 4 studies that evaluated outcomes among patients with 1–2 SSPs ,10 mm. There are several challenges to inter- preting and comparing these studies, including varying defi- nitions of the baseline serrated polyp group and the outcome evaluated. For baseline serrated polyp group characterization, some studies restrict the group to SSPs, and others include SSPs plus TSA and large HP. For follow-up outcomes at surveillance, some used a definition of high-risk neoplasia that included con- ventional advanced adenoma (Table 3), while others used a defi- nition that included conventional advanced adenoma, 3 or more conventional adenomas and/or SSPs, and SSPs or serrated polyp $10 mm. The varied ways studies of serrated polyp outcomes have characterized baseline findings and follow-up outcomes make the literature a major challenge to interpret. Studies reviewed included a multiple cohort study that iden- tified patients with serrated polyps vs those with conventional adenomas, who all had follow-up colonoscopy (n 5 255).48 In this study, the serrated polyp group was defined by having SSP, TSA, or HP $10 mm. Primary outcomes were advanced adenoma (defined as adenoma $10 mmor with villous component orhigh- grade dysplasia) and advanced serrated polyp (defined as HP or SSP $10 mm, SSP with dysplasia, or TSA). Rate of metachronous advanced neoplasia was 20.7% (6 of 29) in patients with baseline conventional advanced neoplasia, and 6.3% (7 of 111) in the isolated serrated polyp group.48 Metachronous advanced ser- rated polyps (defined as HP or SSP $10 mm, SSP with dysplasia, orTSA ofany size) were noted in 10%(3 of30)and 12.5% (2of16) of patients with baseline serrated polyps and nonadvanced ade- nomas or advanced adenomas, respectively, and 5.4% (6 of 111) with isolated serrated polyps. Another multiple cohort study identified 4 baseline groups of patients who received surveillance colonoscopy: 1) low-risk conventional adenoma; 2) low-risk SSP (defined as 1–2 polyps ,10 mm) 6 conventional adenoma; 3) high-risk conventional adenoma and/or $3 conventional ade- nomas; and 4) low-risk SSP plus high-risk conventional adenoma or $3 conventional adenomas 6 SSPs.49 SSP was defined by having histologically confirmed SSP. The primary outcome was advanced neoplasia, defined as adenoma or serrated polyp $10 mm or villous histology, or high-grade dysplasia, or CRC. Stratified by baseline group, the rate of advanced neoplasia (in- cluding large serrated polyp) was 18.2% with low-risk adenoma plus any SSP, 7.8% for low-risk adenoma without SSP, 17.9% for 1–2 SSP ,10 mm, 15.9% for high-risk adenoma and/or $3 conventional adenomas without SSP.49 This suggests that having both conventional advanced neoplasia and SSP of any size could be associated with increased risk for having metachronous ad- vanced neoplasia, defined as adenoma or serrated polyp $10 mm or adenoma with villous histology, or adenoma with high-grade dysplasia, or CRC. A very small study of 75 patients with histo- logically confirmed SSP at baseline suggested that those with synchronous high-risk adenoma (multiple adenomas or ad- vanced adenoma), but not those with low-risk adenoma or absence of synchronous neoplasia, had increased risk for advanced neoplasia on follow-up, compared to samples of indi- viduals with conventional high-risk adenoma, conventional low- risk adenoma, or normal colonoscopy at baseline.50 The largest study to date has been a cohort study of 5433 individuals with baseline colonoscopy and at least 1 surveillance colonoscopy $1 years after initial examination. Baseline cate- gories included presence of normal colonoscopy, low-risk ade- noma, high-risk adenoma, and/or SSP (defined as histologic SSP or TSA).41 Primary outcomes assessed on follow-up included risk for metachronous conventional high-risk adenoma, as well as large serrated polyp (HP, SSP, or TSA) $10 mm. Findings are summarized in Table 6. Rate of high-risk adenoma among patients with SSP but no synchronous high-risk adenoma was just 2.9%, much lower than the observed rate for individuals with isolated high-risk adenoma at baseline of 18.2%. Rate of high-risk adenoma was markedly higher in patients with both SSP and high-risk adenoma at baseline, estimated at 46.4%. Rate of ser- rated polyp $10 mm (HP, SSP, or TSA) at follow-up was sub- stantially higher among patients with isolated SSP vs high-risk adenoma at baseline (9.6% vs 1.0%). Among patients with low- risk adenoma plus SSP at baseline, the rate of metachronous high- risk adenoma was 18.4% (9 of 49) and metachronous SSP $10 mm was 8.2% (4 of 49; Anderson JC, Butterly LF, Robinson CM, personal communication, March 14, 2018). These findings suggest that patients with isolated SSP have low rates of meta- chronous conventional high-risk adenoma unless they have synchronous conventional adenomas at baseline. However, patients with SSP at baseline appear to be at increased risk for metachronous large serrated polyps $10 mm (HP, SSP, or TSA), irrespective of whether concurrent conventional adenomas are present. While this is the largest study to date of metachronous findings among patients with and without SSPs, a limitation is that the risk estimates remain imprecise, owing to the relatively small number of patients with SSP at baseline available for Table 6 Risk for High-Risk Adenoma and Large Serrated Polyps Stratified by Baseline Colonoscopy Findings in the New Hampshire Colonoscopy Registry Baseline finding Surveillance colonoscopy finding HRA,a % (n) SPb ‡10 mm, % (n) No adenoma 4.8 (116/2396) 0.7 (18/2396) LRAc 9.7 (96/991) 0.5 (5/991) HRA 18.2 (11/603) 1.0 (6/603) LRA 1 SSP 18.4 (9/49) 8.2 (4/49) HRA 1 SSP 46.4 (13/28) 3.6 (1/28) SSA/Pd 2.9 (3/104) 9.6 (10/104) SP $10 mm 3.1 (2/65) 12.3 (8/65) NOTE. From Anderson et al,41 adapted with permission. Previously unpublished data provided through personal communication with JC Anderson, LF Butterly, CM Robinson, March 14, 2018, with permission. HRA, high-risk adenoma; LRA, low-risk adenoma; SSA/P, sessile serrated adenoma/polyp. aHRA includes advanced neoplasia or .2 adenomas. bSP includes HP, SP, or TSA. cLRA includes 1–2 adenomas ,10 mm in size. dIncluded TSA in SSA/P group. © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 425 evaluation in the various risk strata. In contrast to the afore- mentioned even smaller studies, however, it is interesting to note that patients with isolated SSP of any size as well as HPs $10 mm were not found to have increased risk for conventional high-risk adenoma on follow-up. Taken together, very low quality of evidence exists to support recommendations for surveillance after removal of 1–2 SSPs ,10mm. Specifically, subgroupsdescribing outcomes in those with serrated lesions are small and there are very limited data on sub- sequentriskfor the most importantoutcomes (ie, CRC). The largest traditional cohort study suggests patients with isolated SSPs have low risk for traditionally defined high-risk adenomas, those with synchronous SSPs and conventional adenoma may have high risk for traditionally defined high-risk adenomas, and that all patients with SSPs are at elevated risk for large serrated polyps on follow-up. Smaller studies at higher risk of bias that used disparate definitions of predictors and outcomes are variably consistent with these observations.Taking into account the absence of consistent, higher- quality evidence, uncertainty regarding implications of having a large serrated polyp at follow-up on CRC risk, and the known challenges of adequate detection51 and complete resection of SSPs,52 the Task Force recommends patients with 1–2 SSPs ,10 mm re- ceive repeat colonoscopy in 5–10 years until new evidence can clarify risk for this group. The recommendation for 5- to 10-year follow-up of patients with 1–2 SSPs ,10 mm is more aggressive than the recommendation for 7- to 10-year follow-up of patients with 1–2 isolated conventional adenomas because the evidence base tosupportlongerfollow-upfor1–2isolatedconventionaladenomas is strong, whereas the evidence base to support follow-up recom- mendations for individuals with 1–2 SSPs ,10 mm is weak. For patients with TSA completely removed at a high-quality examination, repeat colonoscopy in 3 years. (Weak recom- mendation, very low quality of evidence) We found little new evidence to guide the follow-up recom- mendation for patients with TSA. A cross-sectional study com- pared risk for advanced neoplasia and/or $3 adenomas at surveillance colonoscopy for patients with prior isolated TSA (n 5 186) vs a group of age-/sex-matched patients with prior conventional adenoma (n 5 372). Proportion with metachro- nous high-risk adenoma was higher in the TSA vs conventional adenoma group (47.3% vs 32.0%), and associated with higher risk on adjusted analyses (high-risk adenoma OR, 2.37; 95% CI, 1.55–3.63),53 supporting our recommendation for repeat colo- noscopy in 3 years after TSA diagnosis. For patients with 3–4 SSPs ,10 mm at high-quality ex- amination, repeat colonoscopy in 3–5 years. (Weak recom- mendation, very low quality of evidence) For patients with any combination of 5–10 SSPs ,10 mm at high-quality examination, repeat colonoscopy in 3 years. (Weak recommendation, very low quality of evidence) We were unable to identify published articles that specifically examined risk for metachronous neoplasia in patients with 3–10 SSPs, or any combination of 3–10 SSPs and conventional ade- nomas. The previously mentioned unpublished data on 49 patients with a combination of low-risk adenoma and SSP at baseline with unknown total number suggests increased risk for metachronous advanced neoplasia and for large SSP. In the ab- sence of additional data, we have chosen to recommend 3- to 5- year repeat colonoscopy for individuals with 3–4 SSPs ,10 mm, and 3-year repeat colonoscopy for individuals with 5–10 SSPs ,10 mm. These are the same recommendations provided for individuals in the groups with 3–4 and 5–10 isolated conventional adenomas, respectively. Future research may clarify whether patients with a combination of ,10-mm SSPs and conventional adenomas have a distinct risk that should merit different management. For patients with SSP ‡10 mm at a high-quality examina- tion, repeat colonoscopy in 3 years. (Weak recommendation, very low quality of evidence) For patients with HP ‡10 mm, repeat colonoscopy in 3–5 years. A 3-year follow-up interval is favored if concern about pathologist consistency in distinguishing SSPs from HPs, quality of bowel preparation, or complete polyp excision, whereas a 5-year interval is favored if low concerns for con- sistency in distinguishing between SSP and HP by the pa- thologist, adequate bowel preparation, and confident complete polyp excision. (Weak recommendations, very low quality of evidence) We found little new evidence to guide management of patients with SSP $10 mm or HP $10 mm. In the previously cited New Hampshire Colonoscopy registry study, among 65 patients with large serrated polyps (HP, SSP, or TSA), 3.1% had high-risk adenoma on follow-up compared to 4.8% among 2396 patients with no adenoma at index colonoscopy.41 However, having any serrated polyp $10 mm in size was as- sociated with increased risk for large serrated polyp ($10 mm SSP, TSA, or HP), ranging from an absolute risk of 12.3% (8 of 65) for no concurrent conventional adenoma to 11.2% (2 of 18) for concurrent high-risk adenoma, compared to an absolute risk of 0.7% (18 of 2396) for those without adenoma or any serrated polyp. Thus, based on this new evidence, the impli- cations of having a large serrated polyp on risk for subsequent conventional high-risk adenoma are uncertain. However, having a large serrated polyp at baseline does appear to be associated with risk for subsequent large serrated polyps. A challenge in interpreting available literature is a lack of data separating outcomes for those with $10 mm SSP, TSA, and HP. Because of variation in consistent distinction by pathol- ogists between SSPs and HPs in usual care,42–47 a conservative approach might be to assume all HPs $10 mm are SSPs. However, this may subject some patients (especially if con- sultant pathology expertise in distinguishing SSPs from HPs is high) to overdiagnosis and more aggressive surveillance than necessary if rates of advanced neoplasia or large serrated polyp on follow-up among individuals with large SSPs vs large HPs differ. An added problem in making recommendations for large serrated polyps is the potential challenge of resection of SSPs $10 mm. For example, Pohl et al52 reported 47% of SSPs 10–20 mm had evidence of incomplete resection. Given uncertainties regarding implications of having serrated polyp $10 mm and whether outcomes differ for those with SSP vs HP $10 mm, as well as observed variation in ability of pathologists to distinguish SSPs from HPs, and the known challenge of resection of $10 mm SSPs, the Task Force recommends 3-year follow-up for individuals with SSP $10 mm in size, and 3- to 5- year follow-up for individuals with HP $10 mm. For HP $10 mm, a 3-year follow-up interval is favored if concern about consistency in distinction by the consult pathologist between SSP and HP, adequacy of bowel preparation, or complete excision, whereas a 5-year interval is favored if there are limited concerns about consult pathologist ability to dis- tinguish SSP from HP, adequacy of bowel preparation, or The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 426 complete polyp excision. The Task Force acknowledges the importance of accurate polyp size estimation for this recom- mendation and recommends photo documentation verifying polyp size relative to an open forceps or open snare of known size. For patients with SSP containing dysplasia at a high-quality examination, repeat colonoscopy in 3 years. (Weak recom- mendation, very low quality of evidence) No new evidence regarding outcomes of surveillance in individuals with isolated SSP containing dysplasia was identified. SSP with dysplasia is rare; in one series of 179,111 patients with polyps submitted for histologic examination, of 2139 SSPs identified, 302 contained low- or high-grade dysplasia.54 Dysplastic SSPs have more features consistent with CRC than SSPs without dysplasia. In absence of addi- tional data on whether metachronous neoplasia risk differs for individuals with SSP and dysplasia compared to SSP without dysplasia, the Task Force recommends repeat colonoscopy in 3 years after SSP with dysplasia diagnosis, as long as a high-confidence complete resection of the lesion was performed. For patients with history of baseline adenoma removal and 1 subsequent colonoscopy, recommendations for subsequent surveillance should take into account findings at baseline and first surveillance (Table 7). (Weak recommendation, low quality of evidence) We identified several studies on serial surveillance pub- lished since 2012.30,55–59 Findings from the largest of these studies,30,55,56 as well as those considered as part of the 2012 recommendations, are summarized in Table 8. Across all studies, individuals with low-risk adenoma at baseline and no adenoma at first surveillance had low rates of high-risk adenoma on follow-up, ranging from 1% to 6.6%. Similarly, across all but one of the studies reviewed, individuals with high-risk adenoma at both baseline and subsequent surveil- lance examination have .18% rate of metachronous high-risk adenoma on follow-up, supporting our recommendation for follow-up colonoscopy in 3 years. However, the outcomes at second surveillance for other clinical scenarios of baseline and first surveillance findings are more variable across studies. Our recommendations for second surveillance colonoscopy based on findings at baseline and first surveillance are sum- marized in Table 7. More evidence is needed to clarify the best intervals for surveillance in patients who have had baseline and repeat colonoscopy, particularly for those with low-risk adenoma at baseline and follow-up. Also, new evidence is required to guide serial surveillance of individuals with SSPs and large HPs. There is insufficient evidence to recommend use of cur- rently published prediction models for polyp surveillance recommendations. (Weak recommendation, very low quality of evidence) Multiple models have been developed to stratify the risk of metachronous neoplasia and guide surveillance.27,30,58,60–64 Results are promising, but incremental value over current risk- stratification recommendations informed by number, size, and histology of polyps is unclear. For example, a comprehensive model including polyp size, villous histology, proximal loca- tion, and number of adenomas had a superior C-statistic compared with the 2012 Task Force guidelines, but the mag- nitude of improvement was small (0.71 for the model vs 0.66 for 2012 guidelines).30 An important limitation of current published work is that many of these studies have not included a test and independent validation set, raising concerns about Table 7 Recommendations for Second Surveillance Stratified by Adenoma Findings at Baseline and First Surveillance Baseline finding Recommended interval for first surveillance Finding at first surveillance Recommended interval for next surveillance 1–2 tubular adenomas ,10 mm 7–10 y Normal colonoscopya 10 y 1–2 tubular adenomas ,10 mm 7–10 y 3–4 tubular adenomas ,10 mm 3–5 y Adenoma $10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high grade dysplasia; or 5–10 adenomas ,10 mm 3 y 3–4 tubular adenomas ,10 mm 3–5 y Normal colonoscopya 10 y 1–2 tubular adenomas ,10 mm 7–10 y 3–4 tubular adenomas ,10 mm 3–5 y Adenoma $10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high grade dysplasia; or 5–10 adenomas ,10 mm 3 y Adenoma $10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high-grade dysplasia; or 5–10 adenomas ,10 mm 3 y Normal colonoscopya 5 y 1–2 tubular adenomas ,10 mm 5 y 3–4 tubular adenomas ,10 mm 3–5 y Adenoma $10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high grade dysplasia; or 5–10 adenomas ,10 mm 3 y aNormal colonoscopy is defined as colonoscopy where no adenoma, SSP, or CRC is found. © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 427 generalizability.27,30,60,61 Additionally, the range of variables utilized as part of models varies considerably. Notably, models reviewed here suggest the best predictors of future risk for advanced neoplasia remain baseline colonoscopy polyp findings. Evidence is insufficient to recommend differential man- agement for patients with proximal adenoma. (Weak recom- mendation, very low quality of evidence) Among patients with 1–2 adenomas ,10 mm in size, having at least 1 proximal adenoma was associated with increased risk for metachronous advanced neoplasia in a pooled analysis of 7 prospective studies.24 In another study, among patients with any adenoma, having at least one proximal adenoma was associated with 1.17-fold increased risk for any metachronous adenoma, but no increased risk for metachronous advanced neoplasia.65 A co- hort study in the Netherlands of 2990 patients diagnosed with adenoma from 1988 to 2002 and followed through 2008 with medical record review found proximal location was associated with a 1.6-fold increased risk for advanced adenoma at follow- up.30 As mentioned previously, a study of intermediate risk (1–2 .10 mm adenomas or 3–4 adenomas any size) found that proximal adenoma was associated with increased risk for incident CRC,19 but another study found similar risk for incident CRC among individuals with 1–2 proximal only vs distal only adeno- mas ,10 mm in size.18 Taken together, given these varying results, more research is needed to determine whether proximal adenoma location should be considered as a specific factor for modifying surveillance recommendations. For patients with piecemeal resection of adenoma or SSP >20 mm, repeat colonoscopy in 6 months. (Strong recom- mendation, moderate quality of evidence) Piecemeal polyp resection contributes to risk for metachronous neoplasia. A meta-analysis by Belderbos et al66 of 33 studies found risk for recurrent neoplasia was 20% for piecemeal vs just 3% for en bloc resection utilizing endoscopic mucosal resection (EMR) technique. In the subgroup with EMR of polyps 10–20 mm in size, piecemeal resection was associated with an 18% risk for recurrent neoplasia, similar to the 19% rate observed for polyps 20–30 mm and .30 mm in size. Pohl et al52 studied rate of incomplete re- sectionusingbiopsyimmediatelyafterassumedcomplete resection of 5–20 mm polyps, including patients with and without EMR. Incomplete resection was more common with piecemeal (20%) vs en bloc resection (8.4%), but piecemeal resection was not an in- dependent predictor ofincomplete resection after adjusting for size and histology. For polyps $20 mm, additional articles67,68 since the Belderbos et al meta-analysis have reported high risk for recurrent neoplasia associated with piecemeal vs en block resection. These findings suggest that colonoscopists must emphasize complete polyp excision at baseline and, particularly for polyps $20 mm in size, consider strategies for verifying complete excision. The evi- dence base to support management of patients with polyps $20 mm in size resected piecemeal has been reviewed in detail in the recent Task Force recommendations on endoscopic removal of colorectal lesions.69 Basedon the evidence reviewed, the Task Force recommended patients with polyps $20 mm resected piecemeal have first surveillance colonoscopy at approximately 6 months, second surveillance 1 year from first surveillance, and third sur- veillance 3 years from the second surveillance. Other Risk Factors for Metachronous Neoplasia Since the 2012 recommendations, a number of studies have reported on risk factors for metachronous neoplasia. Smoking may be associated with risk for recurrent conventional adenoma as well as serrated polyps.70,71 Environmental factors, such as rural vs ur- ban residence, may contribute to risk for cancer after advanced adenoma removal.72 Metabolic syndrome71,73,74 (as well as com- ponents of this diagnosis, such as increased waist to hip ratio, increased hip circumference) and obesity73–75 have been reported by a number of studies to be associated with increased risk for recurrent neoplasia. Race does not appear to modify risk for re- current adenoma and metachronous advanced neoplasia. A ret- rospective cohort study of 246 whites and 203 black patients who had an adenoma at baseline and at least 1 surveillance colonoscopy found similar rates of recurrent adenoma and advanced neo- plasia.76 A cohort study of participants in the Polyp Prevention Trial compared risk for metachronous adenoma and advanced neoplasia among 1668 white and 153 black patients with adenoma at baseline, all of whom received surveillance colonoscopy, found no difference in rate of metachronous adenoma or advanced neoplasia.77 Thus, while there is evidence that black patients have a higher age-adjusted incidence and mortality from CRC and de- velop CRC at a younger age than other racial and ethnic groups in the United States, once screened, there is no robust evidence that black race modifies the risk for recurrent adenoma or advanced neoplasia. Having a flat adenoma may increase risk for recurrent neoplasia, but more data are needed to support differential man- agement.78 Diet might modify risk, but new evidence to support its impact is limited. One study found no clear association between Table 8 Risk for Neoplasia at Second Surveillance Stratified by Findings at Baseline and First Surveillance Baseline finding First surveillance finding HRA at second surveillance, % Morelli et al, 201355 (n 5 965) Park et al, 201556 (n 5 2087) van Heijningen, et al, 201330 (n 5 1482)a Pinsky et al, 2009109 (n 5 1032)a Laiyemo et al, 2009110 (n 5 1297) Robertson et al, 2009111 (n 5 564) LRA No adenoma 6.6 6.0 1.0 3.9 2.8 4.9 LRA 13.8 10.6 1.0 5.7 4.7 9.5 HRA 18.0 16.4 0.0 15.6 6.9 20.0 HRA No adenoma 9.6 6.7 4.0 5.9 4.8 12.3 LRA 14.0 24.3 3.0 6.7 8.9 13.6 HRA 22.0 38.2 4.0 19.3 30.6 18.2 HRA, high-risk adenoma; advanced adenoma or $3 adenomas; LRA, low-risk adenoma; 1–2 nonadvanced adenomas. aRisk and outcome characterized based on nonadvanced and advanced adenoma. The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 428 fruit and vegetable intake and risk for adenoma recurrence,79 and anotherpooled study of 1727participants from 2 randomized trials did not identify a relationship between proinflammatory diet and risk for adenoma, advanced adenoma, or 3 or more adenomas on follow-up colonoscopy after initial polypectomy.80 Lifestyle factors, such as increased sedentary behavior, may increase risk for ade- noma recurrence,81 but it is unclear whether specifically modifying behavior will reduce risk. Since 2012, several studies have been published on chemo- preventive strategies for reducing risk for recurrent neoplasia. A large, well-done randomized controlled trial found that supple- mentation with calcium or vitamin D (alone or in combination) was not associated with reduced risk for recurrent neoplasia,82 and a small study that included intervention with calcitriol, as- pirin, and calcium also found no benefit on risk for recurrent neoplasia.83 A prospective cohort study reported that dietary supplement use was not associated with reduced risk of meta- chronous neoplasia.84 An observational study demonstrated that exposure to metformin was associated with reduced risk for finding adenoma at surveillance colonoscopy among diabetics,85 and a pilot randomized controlled trial of nondiabetic subjects found that low-dose metformin was associated with reduced risk for recurrent adenoma at 1 year,86 suggesting metformin may be a promising chemopreventive agent warranting further study. Newly published work has confirmed that aspirin and expo- sure to nonsteroidal anti-inflammatory medications may reduce risk for adenoma recurrence, but optimal dose, mechanism of action, and characteristics of patients most likely to benefit have not been well established.87,88 While there is insufficient evidence to support routine recommendation of aspirin for cancer and adenoma prevention in patients with baseline adenoma, the overall impact of aspirin on cardiovascular disease (CVD) and CRC risk reduction might support recommending aspirin for some patients. Specifically, it should be noted that, for patients aged 50–59 years who have $10% risk for CVD and life expec- tancy of $10 years, without increased risk for bleeding, the US Preventive Services Task Force has recommended use of aspirin 81 mg per day for primary prevention of both CVD and CRC (grade B recommendation), and has recommended that aspirin could also be considered for patients aged 60–69 years based on shared decision making, taking into account potential harms and benefits (grade C recommendation).89 Thus, for patients who inquire about strategies to reduce future CRC risk after poly- pectomy, an opportunity exists to recommend estimation of cardiovascular risk and to consider aspirin for both CVD and CRC risk reduction if these criteria are met. In summary, there is little evidence that lifestyle factors, such as diet, smoking, obesity, and sedentary behavior, increase the risk of metachronous neoplasia, or that modification of these behaviors reduces the risk. Likewise, there is little new evidence that chemoprevention impacts the risk of metachronous ad- vanced neoplasia in patients with adenoma. At this time, there is insufficient evidence to recommend modification of surveillance intervals based on these factors. More work needs to be done to identify risk factors and chemopreventive strategies that can re- duce risk for metachronous neoplasia and possibly allow for less frequent surveillance colonoscopy. DISCUSSION Currently, the interval for screening and surveillance colono- scopy is based on stratification of risk for metachronous advanced neoplasia. Since the last recommendations by the Task Force in 2012, evidence to support low risk for incident and fatal cancer after normal colonoscopy has strengthened the recommendation to defer repeat screening for at least 10 years. Among patients with polyps, new data suggest that patients with 1–2 adenomas ,10 mm are at lower than average risk for incident and fatal CRC and can undergo colonoscopy at longer intervals. Individuals with advanced neoplasia appear to remain at a greater than population risk for CRC after polypectomy. New data are emerging to support less frequent surveillance among individuals with 3–4 adenomas ,10 mm in size. The literature on risk for subsequent neoplasia in those with serrated lesions is at an early stage (relative to those with conventional adenomas) and con- tinues to evolve. Those with a combination of both serrated lesions and conventional adenomas appear to be a higher-risk group for subsequent advanced neoplasia. Encouragingly, 2 studies suggest that exposure to surveillance colonoscopy after baseline polypectomy (compared to no surveillance) may reduce risk for incident CRC among high-risk patients, but more data are needed to support the incremental benefit of post-polypectomy surveillance for reducing incidence and mortality from CRC. Given that risk for metachronous advanced neoplasia has been accepted thus far as a surrogate for risk for incident CRC, and the plethora of studies that have examined risk for metachronous ad- vanced neoplasia among individuals with baseline polyps, the Task Force has provided updated recommendations for surveillance based on the relationship of baseline findings to risk for meta- chronous advanced neoplasia. Key updates since the 2012 US Multi-Society Task Force recommendations are summarized in Table 9. Recommendations for patients with advanced adenoma, including those with adenoma $10 mm, or containing high-grade dysplasia and/or villous features are unchanged, with evidence to support close surveillance in 3 years strengthened. One year, rather than a more general recommendation for ,3-year follow-up colonoscopy for individuals with .10 adenomas at a single ex- amination, has been recommended tosimplifyfollow-up, although the evidence base to support this strategy has not been markedly strengthened. Emerging evidence suggests that individuals with 3–4 adenomas ,10 mm are at low risk for metachronous neo- plasia, supporting our recommendation for a 3- to 5-year interval rather than a strict 3-year follow-up colonoscopy for this group of patients. Another significant change from prior guidance is our recommendation for surveillance colonoscopy in 7–10 yearsrather than5–10yearsforpatientswith1–2adenomas,10mm,basedon the growing body of evidence to support low riskfor metachronous advanced neoplasia. In this population, the risk for metachronous advanced neoplasia is similar to that for individuals with no ade- noma (Figure 2). Importantly, the observed risk for fatal CRC among individuals with 1–10 adenomas ,10 mm is lower than average for the general population. The largest cohort study to date including patients with SSPs offers evidence to support follow-up in ,10 years (5–10 years for 1–2 SSPs ,10 mm, 3–5 years for 3–4 SSPs ,10 mm, and 3 years for 5–10 SSPs, SSP $10 mm, or SSP withdysplasia),basedonobservedincreasedriskformetachronous large SSP. Our review highlights several opportunities for research to clarify risk stratification and management of patients post poly- pectomy. In order to optimize risk-reduction strategies, the mechanisms driving metachronous advanced neoplasia after baseline polypectomy and their relative frequency need to be better understood through studies that include large numbers of patients © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 429 with interval cancers and/or advanced neoplasia after baseline polypectomy. Mechanisms may include new/incident growth, in- complete baseline resection, and missed neoplasia; each of these potential causes may require different interventions for improve- ment.90 For example, if mostinterval cancers after polypectomy are attributable to missed neoplasia,91,92 redoubled focus on quality of baseline examination may be indicated. Indeed, quality factors, such as incomplete examination and poor bowel preparation, have been associated with risk for cancer after polypectomy.19,30,31 Fur- ther, it is plausible that the ADR of a colonoscopist, which has been tied closely with risk for interval cancer after normal screening colonoscopy,93,94 might have a similar correlation with risk for in- terval cancer after polypectomy. If incomplete resection is the major cause of metachronous neoplasia after polypectomy,65 focus on implementing strategies that improve polypectomy technique may be indicated. If the main driver is incident neoplasia, then strategies that optimize risk stratification and timing of colono- scopy (early for high risk and deferred for low risk) might be most impactful. Interestingly, one study has found that the attributable fraction of risk for CRC after baseline polypectomy is highest for incomplete polyp removal and not having “on time” follow-up colonoscopy, underscoring the importance of complete removal and appropriate follow-up intervals.31 More work is needed to identify the key drivers of metachronous advanced neoplasia, particularly CRC. Application of precision medicine, such as of- fering chemoprevention to individuals with genotypes associated with response to therapy, may improve effectiveness of chemo- prevention, but requires further study.95 Biomarkers of adenoma recurrence also merit study.96–100 Widespread promotion of colo- noscopistADR as a quality metric is likelytoincreasethefrequency of diagnosing patients with multiple small adenomas. Because finding multiple small adenomas may be a marker of careful colonoscopy, patients with multiple (eg, 1–4) small adenomas may besubjecttoaso-called“adenomadetectorparadox,”inwhichthey are currently recommended short-interval (eg, 3 years) colono- scopy despite potentially having very low risk for incident CRC secondarytohaving a very-high-quality examination.Although we have recommended 3- to 5-year follow-up for individuals with 3–4 small adenomas based on emerging evidence, understanding the implications of having multiple small adenomas should be a key focus of future research. We found few data to guide management of individuals with isolated HPs ,10 mm. Future research should clarify whether these individuals are indeed a low-risk group, as uncertaintiesremainaboutfrequencyofmisdiagnosisofsmallSSPs as HPs, and whether patients with small HPs proximal to the sigmoid colon or in the rectum or sigmoid colon have significantly increasedriskforeitherlargeserratedpolypsoradvancedneoplasia on follow-up. Beyond risk stratification, more fundamental research on the potential benefits of surveillance is needed. In particular, better evidence is needed to support whether exposure to surveillance colonoscopy, compared to no surveillance, reduces CRC in- cidence or mortality. Such evidence is needed given the increasing proportion of patients who are having adenomas detected as part of increased participation in CRC screening. Several areas not covered by our current recommendations also warrant investigation. We do not provide recommendations for management of young patients (,50 years) with incidentally detected adenoma, although evidence to guide management is emerging.101,102 At the other end of the age spectrum, more re- search is needed to determine whether the potential cancer pre- vention and early detection benefits of surveillance outweigh immediate procedure-related risks for individuals older than age 75 years, or with multiple comorbidities. Cost-effectiveness of surveillance, as well as alternative strategies for surveillance (such as fecal immunochemical testing or multi-target fecal immuno- chemical testing–DNA) requires further study. Indeed, one modeling study has suggested that surveillance fecal immuno- chemical testing (rather than colonoscopy) might be effective post-polypectomy.103 As a result of our review, we have several suggestions for best practices to improve the quality and comparability of future re- search on post-polypectomy surveillance. Studies vary in their definitions of high-risk adenoma. Ideally, when considering both predictors and outcomes, we suggest as a best practice reporting presence of individual findings (eg, villous adenoma, SSP, and HP $10 mm) in addition to several potentially clinical relevant sum- mary categories, including advanced neoplasia, advanced ade- noma, and large serrated polyp (HP or SSP $10 mm). Because our understanding oftherisks andoutcomesamong patients with SSPs is still limited, we suggest it is particularly important to separate SSPs from aggregate predictor or outcome categories, such as ad- vanced neoplasia. Further, we suggest specifically reporting SSP, HPs, and TSAs separately as predictors and outcomes, and clearly defining any aggregate categories (such as serrated polyps $10 mm) precisely. Providing histology-specific data will allow for greater comparability across studies, and better assessment of whether outcomes differ by serrated polyp histology. For example, histology-specific outcome data could help elucidate whether individuals with HP $10 mm have outcomes similar to those of patients with SSP $10 mm. More studies are needed that include patients that are racially and ethnically diverse. Most surveillance studies provide limited data on the quality of baseline colonoscopy, which could help in interpreting results. Additionally, we recom- mend that both relative and absolute risks for outcomes, such as metachronous advanced neoplasia, be provided in surveillance Table 9 Key Updates Since 2012 Recommendations Provided in the 2019 US Multi-Society Task Force Recommendations for Follow-Up After Colonoscopy and Polypectomy • New evidence based on risk of colorectal cancer outcomes, rather than based only on risk of advanced adenoma during surveillance, is provided to strengthen polyp surveillance recommendations • 7- to 10-y rather than 5- to 10-y follow-up is recommended after removal of 1–2 tubular adenomas ,10 mm in size (Table 4) • More detailed recommendations for follow-up after removal of serrated polyps have been provided (Table 5) • Importance of high-quality baseline examination has been emphasized • 1 y rather than ,3-y follow-up is recommended after removal of .10 adenomas • Option to recommend 3–5 y instead of 3-y follow-up after removal of 3–4 adenomas ,10 mm in size The American Journal of GASTROENTEROLOGY VOLUME 115 | MARCH 2020 www.amjgastro.com COLON Gupta et al. 430 studies. Absolute risks are key to providing perspective to patients and physicians on the true risk associated with a given polyp- finding scenario. Studies examining the potential benefit of expo- sure to surveillance vs no surveillance should seek to avoid several potential sources of bias. First, risk for cancer associated with ad- enoma is often compared to the general population, not to people who had normal colonoscopy. Comparing cancer risk among individuals with adenoma removal to a general population without ascertaining for presence of CRC or adenoma may bias towards underestimating risk reduction that can be gained by removing adenomas.8,16,17,104 Second, risk for cancer associated with surveil- lance is often compared to the general population, not to people whohadpolypectomybutnosurveillance;thismaybiastowardsan overestimation of the benefit of surveillance.8,15,16 Also, risk for cancer associated with surveillance often excludes cancers di- agnosed within 1 year, which may bias towards overestimating benefit of surveillance because in usual practice, surveillance time frames are assigned based on initial results, not initial results plus clinical course within a year.16,105 Finally, some studies may com- pare outcomes among patients who did not receive surveillance to those who survived cancer free and received surveillance.19 This is analogous to a per-protocol analysis of a randomized trial, may overestimate the benefit of surveillance, and may be considered a form of immortal time bias. Additionally, we note that very few randomized trials of surveillance strategies have been done. In the United States, the National Polyp Study is the only randomized controlled trial of surveillance colonoscopy. This study was con- ducted in the 1980s before availability of modern technology (eg, high-definition colonoscopies) and widespread awareness of im- portance of quality on outcomes, employed a highly aggressive baselinepolyp-clearing strategy, andcompared a veryshort 1-vs3- year follow-up interval among patients with baseline adenoma.106 The European Polyp Surveillance trial, which includes arms ran- domized to different surveillance intervals based on specific base- line polyp-finding strata, is well underway and will likely offer new insights to guide polyp surveillance.107 Lack of randomized trials in the area of surveillance is quite remarkable, given the frequency of surveillance colonoscopy in usual practice and in the context of the many trials that are available on CRC screening. Several limitations may be considered in interpreting and applying our recommendations to practice. Our recom- mendations for surveillance intervals depend on the performance of a high-quality examination (as evidenced by examination complete to the cecum with adequate bowel preparation and complete polyp resection) by a high-quality colonoscopist (based on adequate ADR). This requires that colonoscopists continu- ously strive to improve quality, but also use caution in applying surveillance recommendations when concerns about quality ex- ist. We focused on updating our recommendations based on a literature review of articles published since the prior recom- mendations were issued in 2012, and did not perform pooled or meta-analyses. A more comprehensive literature review of all articles published relevant to surveillance over a longer time pe- riod, as well as meta-analyses, were beyond the scope of this work. In many cases, our recommendations are based on very-low- or low-quality evidence. Even where evidence was judged to be of moderate or high quality, few studies were randomized trials. Thus, future research has a high likelihood of producing evidence that may change recommendations, particularly those based on lower-quality evidence. We recognize the challenge of applying new recommendations in practice, such as a 7- to 10-year, rather than a 5- to 10-year follow-up recommendation for patients with 1–2 adenomas ,10 mm. Patients, primary care physicians, and colonoscopists may have concerns about lengthening a pre- viously recommended interval, and will need to engage in shared decision making regarding whether to lengthen the follow-up interval based upon the guidance here or utilize the recommen- dation made at the time of the prior colonoscopy. CONCLUSIONS CRC incidence and mortality are decreasing secondary to improvements in risk factor exposures, screening, treatment, and perhaps exposure to surveillance among patients with polyps.108 Given that some patients with polyps appear to have persistently increased risk for CRC, and many have increased risk for advanced neoplasia on follow-up, surveillance colonoscopy to attempt to re- duce CRC risk is clinically rational and recommended. Evidence to support best practices for surveillance colonoscopy has strength- ened and has helped to support close follow-up for some groups, as wellaslessintensefollow-upforothers.Moreworkisneededtofully understand which patient populations are most likely to benefit from surveillance, and the ideal surveillance interventions to apply for optimizing CRC prevention and early detection. ACKNOWLEDGMENTS The views expressed in this article are those of the author(s) and do not necessarily represent the views of the Department of Veterans Affairs. The authors thank Karen Heskett, medical librarian, UC San Diego, for her assistance with conduct of our literature review. CONFLICTS OF INTEREST Conflicts of interest The authors disclose no conflicts of interest relative to the current work since 2016. Industry relationships for authors (consulting, research, reimbursement) without conflicts of interest relevant to the current work since 2016: Douglas K. Rex (Olympus, Boston Scientific, Covidien, Lumendi, Salix, Aries, Cook Medical, ERBE, Bausch Health Inc, Novo Nordisk, Endochoice, Braintree Laboratories, Norgine, Endokey, EndoAid, Medivators, Satisfai Health); Sapna Syngal (Chirhoclin, Cook, Myriad Genetics, Inc, DC Health, Inc); David Lieberman (Covidien, Freenome Holdings, Inc, Ironwood, Check-Cap, CEGX); Douglas Robertson (Covidien, Freenome Holdings, Inc, Amadix); Tonya Kaltenbach (Aries Pharmaceuticals, Micro-Tech Endoscopy, Olympus, Boston Scientific, Medtronic); Aasma Shaukat (None); Samir Gupta (Freenome Holdings, Inc, Guardant Health, Inc, Mallinckrodt Pharmaceuticals); Carol Burke (Salix Pharmaceuticals, Ferring Pharmaceuticals, Aries Pharmaceuticals, Intuitive Surgical, Pfizer, Covidien, Boston Scientific, US Endoscopy, Abbvie Cancer Pre- vention Pharmaceuticals, Janssen Pharmaceuticals; SLA Pharma AG; Freenome Holdings, Inc). Jason Dominitz (None); Joseph C. Anderson (None). Funding This work was supported in part by the National Cancer Institute (NCI) of the National Institutes of Health (NIH) under Award Number R37 CA222866 and the Department of Veterans Affairs under Award Number I01 HX001574, as well as NIH awards P30CA06516 and UO1 CA864000. Abbreviations used in this paper: ADR, adenoma detection rate; CI, confidence interval; CRC, colorectal cancer; CVD, cardiovascular dis- ease; EMR, endoscopic mucosal resection; HR, hazard ratio; SIR, standardized incidence ratio; SSP, sessile serrated polyp; HP, © 2020 by the American College of Gastroenterology, the AGA Institute, and the American Society for Gastrointestinal Endoscopy. The American Journal of GASTROENTEROLOGY COLON Immunosuppression in Autoimmune Hepatitis 431 hyperplastic polyp; OR, odds ratio; RR, relative risk; TSA, traditional serrated adenoma. REFERENCES 1 Heitman SJ, Ronksley PE, Hilsden RJ, et al. 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