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, colonoscopists 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 polyps 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, location, 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 colonoscopy 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 increasingly 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 technologies (eg, high-definition colonoscopes). Higher-quality colonoscopy 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, https://links.lww.com/AJG/B394 [SG and DL, with input from TK]). In consultation 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 Supplementary Appendix B, https://links.lww.com/AJG/B395 for search terms). English-language articles since January 1, 2012 were retrieved. Searches were run on March 30, 2017, and identified a total of 1904 unique articles (see Supplementary Appendix C, https://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 abstract review. All abstracts were reviewed by 2 authors (SG and DL) and potentially relevant abstracts were selected for full article review. Included articles were reviewed in detail by the same 2 authors. The final list of articles selected for review was supplemented by repeating the literature search through September 2018 to identify articles published since the time of the literature search, as well as through opportunistic identification of additional relevant articles. References directly relevant to final recommendations were identified through joint consensus (SG and DL). Based on prior findings and the current literature review, post-colonoscopy management recommendations were developed by 2 authors (SG and DL) and refined through consensus discussion with all authors after circulating both draft recommendations and a table summarizing key findings of articles that were included for article review. For each recommendation, the quality of evidence (Table 2) and strength of recommendation were rated using our previously described approach.3 Strong recommendations mean that most informed patients would choose the recommended management and that clinicians can structure their interactions with patients accordingly. Weak recommendations mean that patients’ choices will vary according to their values and preferences, and clinicians must ensure that patients’ care is in keeping with their values and preferences.Table 1: Criteria for Inclusion/Exclusion of Titles, Abstracts, and ArticlesTable 2: Grading of Recommendations Assessment, Development, and Evaluation Ratings of EvidenceThis article does not include recommendations for follow-up for individuals with hereditary CRC syndromes (eg, Lynch syndrome and familial adenomatous polyposis), inflammatory bowel disease, a personal history of CRC (including malignant polyps), family history of CRC or colorectal neoplasia, or serrated polyposis syndrome. As such, our recommendations for follow-up after colonoscopy and polypectomy do not apply to these groups except in cases where polyp findings would result in a shorter colonoscopy interval than indicated based on the status of these clinical conditions. Further, recommendations for polypectomy technique were outside the scope of this article. Notably, the Task Force has recently issued recommendations for follow-up colonoscopy for individuals with Lynch syndrome4 and a personal history of CRC.3,5,6 Recommendations for follow-up of serrated polyposis syndrome, management of patients with a malignant polyp, as well as optimal polypectomy technique will be covered in subsequent Task Force recommendations. Report Format The primary goals of colonoscopy screening and post-polypectomy surveillance are to reduce CRC incidence and mortality. We provide a review of the available evidence on the impact of surveillance on these outcomes. Next, we provide recommendations for follow-up strategies, with a summary of new evidence, including an overall assessment of the quality of evidence and strength of recommendations. This is followed by a summary of key limitations of existing evidence, future research opportunities, and best practices for research in the field. Given the large amount of data on post-colonoscopy follow-up, we focus primarily on new publications since the Task Force recommendations in 2012. Terms, Definitions, and Colonoscopy Quality Assumptions Polyp terms and definitions. The polyp surveillance literature varies in terms used for predictors and outcomes and associated definitions (Table 3). In this report, normal colonoscopy refers to a colonoscopy where no adenoma, sessile serrated adenoma/polyp or sessile serrated polyp (SSP), hyperplastic polyp (HP) ≥10 mm, traditional serrated adenoma (TSA), or CRC was found. We consider individuals with only HP <10 mm as having had normal colonoscopy. To summarize prior evidence, “low-risk adenoma” refers to having 1–2 tubular adenomas with low-grade dysplasia, each <10 mm in size. There are 2 higher-risk categories commonly described in the published literature, one based on size and histology (advanced neoplasia), and the other based on number of adenomas (multiple adenomas). Advanced neoplasia is defined as an adenoma ≥10 mm, adenoma with tubulovillous or villous histology, adenoma with high-grade dysplasia, or presence of invasive cancer. An adenoma with size ≥10 mm, with tubulovillous or villous histology, or with high-grade dysplasia in the absence of invasive CRC is commonly referred to as an advanced 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 neoplasia 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 advanced neoplasia, and will refer to these lesions separately.Table 3: Terms and DefinitionsaWe 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 because evidence supporting level of risk for various criteria are constantly evolving, and because prior terminology may be confusing (eg, use of high-risk adenoma to refer to both advanced neoplasia and/or having 3 or more adenomas) and limit precise risk stratification. All recommendations assume the colonoscopist has performed a high-quality examination (Table 3). Colonoscopy quality assumptions. For the purposes of this review, we have defined high quality based on colonoscopist performance, such as adequate adenoma detection rate (ADR), and examination-specific characteristics, such as examination complete 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 proportion 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 documentation is important for lesions such as HPs, where small size (<10 mm) is associated with well documented low risk for subsequent 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 (regardless 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 cohort study of 304,774 individuals with 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 persistently decreased across a range of years since last normal colonoscopy, 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) for 7–10 years of follow-up.9 A 70% relative risk (RR) reduction was 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% relative reduced risk for fatal CRC among 99,166 who had a normal screening colonoscopy through the traditionally recommended 10-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 colonoscopy procedures. A potential limitation was unmeasured differences 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, suggested 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 available 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 adenoma, despite adenoma removal, may have increased risk for CRC compared to the general population. An Irish cohort study 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 Annual 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 information on polyp size in the registry, limited information on type of follow-up patients received, and incomplete colonoscopy 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 mortality 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 colonoscopy, 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 nonadvanced 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 introducing detection bias; cumulative colonoscopy exposure after 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 adenoma 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 unexposed 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% relative reduction in incident CRC risk (adjusted HR, 0.57 for 1 examination; 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, adenoma 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 surveillance examination. In a higher-risk group defined by having incomplete 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 examination, 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 surveillance 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 reduce risk for incident CRC, particularly among those with baseline 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 colonoscopy (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 increased 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 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 patients are at risk, and will be most for reducing risk. Limitations of prior studies include and subsequent inability to for factors that could be associated with CRC risk and of in surveillance, such as healthy and medical recommendations for follow-up. Risk for incident and fatal CRC among individuals with baseline is uncertain. low quality of evidence) In a study of CRC cases compared to within a cohort of individuals who colonoscopy between and having an was associated with increased for CRC ratio 95% CI, while having with dysplasia was associated with a increased for CRC 95% CI, compared to having no A limitation of this study is that is whether baseline polyps were or only because all patients were identified based on but colonoscopy were not A cohort study of patients included in a sigmoidoscopy screening trial compared CRC risk among patients with ≥10 mm serrated lesions (including an or serrated to risk among patients who had a nonadvanced adenoma, normal sigmoidoscopy, or no to the group with no screening, a nonstatistically significant increased risk for incident CRC was observed in individuals with large serrated polyps (HR, 95% CI, to the normal sigmoidoscopy group, a increased risk for incident CRC was observed in individuals with large serrated polyps (HR, 95% CI, Risk for incident CRC for individuals with advanced adenoma at baseline compared to those with no screening was increased (HR, 95% CI, for histology, size, and number of adenomas, having a large serrated polyp was associated with a increased risk for incident CRC 95% CI, (including no to was observed in large serrated polyps in for a median years of follow-up, that some serrated polyps may be a general of risk rather than an high-risk This study is limited by the small size, and uncertainty whether a group of patients as a result of a sigmoidoscopy trial are of patients routinely with at colonoscopy. data that patients with have increased risk for CRC, the and of risk associated with SSPs is limitations of available studies. of risk for incident and fatal CRC after normal colonoscopy and after polyp removal. published since our last recommendations the evidence to support a low risk for incident and fatal CRC after normal screening colonoscopy is There to be evidence on the incremental effectiveness of a repeat screening colonoscopy at 10 years after normal colonoscopy, but modeling studies studies vary in of risk for incident and fatal CRC after baseline adenoma removal, with some increased risk, and decreased risk. evidence suggests that exposure to surveillance colonoscopy after baseline adenoma removal may reduce CRC risk, but the of benefit associated with exposure to surveillance colonoscopy is individuals with more advanced findings at baseline colonoscopy with poor baseline 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 in the higher-risk Further, groups are most likely to and whether surveillance CRC remains a studies patients with SSPs may have an increased risk for incident CRC, but and of risk remains uncertain. more evidence is to patients are at lowest and risk for incident and fatal CRC after initial colonoscopy, and whether surveillance can improve outcomes. pending of new evidence, we provide colonoscopy surveillance recommendations to patient the and available evidence that some patients remain at risk for CRC despite baseline polypectomy. Surveillance for Colorectal Cancer Risk For patients with high-quality colonoscopy, repeat CRC screening in 10 years. recommendation, high quality of evidence) and modeling studies of colonoscopy and the evidence to support the that individuals with normal colonoscopy are at lower than average risk for CRC, as mentioned Based on this reduced risk, we CRC screening in individuals be 10 years after a normal examination complete to the cecum with bowel preparation adequate to detect polyps >5 mm in size. studies may whether the interval 10 years may be A 10-year follow-up after normal colonoscopy is recommended of 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 4 and US Multi-Society Task Force Recommendations for in Normal Colonoscopy or US Multi-Society Task Force Recommendations for in Recommendations for follow-up after colonoscopy and polypectomy. Recommendations for post-colonoscopy follow-up in average risk adults are 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 risk-stratified repeat colonoscopy are sessile serrated serrated serrated patients with 1–2 tubular adenomas <10 mm in size removed at a high-quality examination, repeat colonoscopy in 7–10 years. recommendation, quality of evidence) The Task Force previously recommended repeat colonoscopy within a range of years for individuals with 1–2 small tubular adenomas. The in recommendation to a interval is based on new studies that and prior evidence to 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 risk for metachronous advanced neoplasia among patients with low-risk adenomas have been The first data from individuals across studies reported between and with years follow-up after baseline colonoscopy. The rate of metachronous advanced

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