Risk Of Metachronous Advanced Neoplasia Research Articles

Serrated Polyps in Inflammatory Bowel Disease Indicate a Similar Risk of Metachronous Colorectal Neoplasia as in the General Population.

The risk of metachronous advanced neoplasia after diagnosing serrated polyps in patients with IBD is poorly understood. A retrospective multicenter cohort study was conducted between 2010 and 2019 at three tertiary centers in Montreal, Canada. From pathology databases, we identified 1587 consecutive patients with serrated polyps (sessile serrated lesion, traditional serrated adenoma, or serrated epithelial change). We included patients aged 45-74 and excluded patients with polyposis, colorectal cancer, or no follow-up. The primary outcome was the risk of metachronous advanced neoplasia (advanced adenoma, advanced serrated lesion, or colorectal cancer) after index serrated polyp, comparing patients with and without IBD. 477 patients with serrated polyps were eligible (mean age 61years): 37 with IBD, totaling 45 serrated polyps and 440 without IBD, totaling 586 serrated polyps. The median follow-up was 3.4years. There was no difference in metachronous advanced neoplasia (HR 0.77, 95% CI 0.32-1.84), metachronous advanced adenoma (HR 0.54, 95% CI 0.11-2.67), and metachronous advanced serrated lesion (HR 0.76, 95% CI 0.26-2.18) risk. When comparing serrated polyps in mucosa involved or uninvolved with IBD, both groups had similar intervals from IBD to serrated polyp diagnosis (p > 0.05), maximal therapies (p > 0.05), mucosal inflammation, inflammatory markers, and fecal calprotectin (p > 0.05). The risk of metachronous advanced neoplasia after serrated polyp detection was similar in patients with and without IBD. Serrated polyps in IBD occurred independently of inflammation. This helps inform surveillance intervals for patients with IBD diagnosed with serrated polyps.

Risk factors for metachronous colorectal cancer and advanced neoplasia following primary colorectal cancer: a systematic review and meta-analysis

BackgroundIdentifying risk factors for metachronous colorectal cancer (CRC) and metachronous advanced neoplasia could be useful for guiding surveillance. We conducted a systematic review and meta-analysis to investigate risk factors for metachronous CRC and advanced neoplasia.MethodsSearches were conducted in MEDLINE, Embase, Web of Science and Cochrane Central Registry of Controlled Trials for articles (searching period: 1945 to Feburary, 2021) that reported the results of an association between any factor and metachronous advanced neoplasia or metachronous CRC. There were no restrictions on the publication date or language. Random effects models were fitted to estimate the combined association between the risk factors and metachronous CRC or advanced neoplasia. The Risk of Bias In Non-Randomised Studies of Interventions tool (ROBINS-I) was used to assess the risk of bias of included studies.ResultsIn total, 22 observational studies with 625,208 participants were included in the systematic review and meta-analysis. Of these, 13 studies investigated risk factors for metachronous CRC and 9 for advanced neoplasia. The risks of metachronous CRC or advanced neoplasia were higher if the first CRC was diagnosed in the presence of a synchronous advanced lesion (pooled risk ratio (RR) from 3 studies: 3.61, 95% confidence interval (CI): 1.44–9.05; and pooled RR from 8 studies: 2.77, 95% CI: 2.23–3.43, respectively). The risk of metachronous CRC was lower, but the risk of metachronous advanced neoplasia was higher if the first CRC was distal (compared with proximal) (pooled RR from 3 studies: 0.48, 95% CI: 0.23–0.98; and pooled RR from 2 studies: 2.99, 95% CI: 1.60–5.58 respectively). The risk of metachronous advanced neoplasia increased with age (pooled RR from 3 studies: 1.07 per year of age, 95% CI: 1.03–1.11). There was no evidence that any lifestyle risk factors studied were associated with the risk of metachronous CRC or advanced neoplasia.ConclusionsThe identified risk factors for metachronous CRC and advanced neoplasia might be useful to tailor the existing surveillance guidelines after the first CRC. There were potential limitations due to possible misclassification of the outcome, confounding and risk of bias, and the findings cannot be generalised to high-risk genetic syndrome cases.

Strategy for post-polypectomy colonoscopy surveillance: focus on the revised Korean guidelines

Background: The risk of metachronous advanced neoplasia is linked to the presence of polyps on initial colonoscopy. Consequently, it is crucial to establish an appropriate colonoscopy surveillance period post-polypectomy.Current Concepts: The US Multi-Society Task Force, the European Society of Gastrointestinal Endoscopy, and the British Society of Gastroenterology revised their respective foreign guidelines in the 2020s. In Korea, a revised edition of post-polypectomy colonoscopic surveillance was announced in 2022, with the following risk factors: (1) adenoma ≥10 mm in size; (2) 3 to 5 (or more) adenomas; (3) tubulovillous or villous adenoma; (4) adenoma containing high-grade dysplasia; (5) traditional serrated adenoma; (6) sessile serrated lesions containing any grade of dysplasia; (7) serrated polyps of at least 10 mm in size; and (8) 3 to 5 (or more) sessile serrated lesions. In these guidelines, suitable surveillance periods are suggested for each risk factor.Discussion and Conclusion: The evidence supporting the best practices for post-polypectomy colonoscopy surveillance has strengthened, helping to support both close follow-up for some populations and less intense follow-up for others.

S1171 Risk of Metachronous Advanced Neoplasia in Patients With Serrated Lesions and Inflammatory Bowel Disease

S1171 Risk of Metachronous Advanced Neoplasia in Patients With Serrated Lesions and Inflammatory Bowel Disease

Korean Guidelines for Postpolypectomy Colonoscopic Surveillance: 2022 revised edition.

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for managing advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of the limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: adenoma ≥10 mm in size; 3 to 5 (or more) adenomas; tubulovillous or villous adenoma; adenoma containing high-grade dysplasia; traditional serrated adenoma; sessile serrated lesion containing any grade of dysplasia; serrated polyp of at least 10 mm in size; and 3 to 5 (or more) sessile serrated lesions. More studies are needed to fully comprehend the patients who are most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Korean guidelines for postpolypectomy colonoscopic surveillance: 2022 revised edition.

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for the management of advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: (1) adenoma ≥10 mm in size; (2) 3 to 5 (or more) adenomas; (3) tubulovillous or villous adenoma; (4) adenoma containing high-grade dysplasia; (5) traditional serrated adenoma; (6) sessile serrated lesion (SSL) containing any grade of dysplasia; (7) serrated polyp of at least 10 mm in size; and (8) 3 to 5 (or more) SSLs. More studies are needed to fully comprehend the patients most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

Korean Guidelines for Postpolypectomy Colonoscopic Surveillance: 2022 Revised Edition

Colonoscopic polypectomy is effective in decreasing the incidence and mortality of colorectal cancer (CRC). Premalignant polyps discovered during colonoscopy are associated with the risk of metachronous advanced neoplasia. Postpolypectomy surveillance is the most important method for managing advanced metachronous neoplasia. A more efficient and evidence-based guideline for postpolypectomy surveillance is required because of the limited medical resources and concerns regarding colonoscopy complications. In these consensus guidelines, an analytic approach was used to address all reliable evidence to interpret the predictors of CRC or advanced neoplasia during surveillance colonoscopy. The key recommendations state that the high-risk findings for metachronous CRC following polypectomy are as follows: 1) adenoma ≥10 mm in size; 2) 3-5 (or more) adenomas; 3) tubulovillous or villous adenoma; 4) adenoma containing high-grade dysplasia; 5) traditional serrated adenoma; 6) sessile serrated lesion (SSL) containing any grade of dysplasia; 7) serrated polyp of at least 10 mm in size; and 8) 3-5 (or more) SSLs. More studies are needed to fully comprehend the patients who are most likely to benefit from surveillance colonoscopy and the ideal surveillance interval to prevent metachronous CRC.

The Risk of Metachronous Advanced Neoplasia After Colonoscopy in Patients Aged 40-49 Years Compared With That in Patients Aged 50-59 Years.

This study investigated the risk of metachronous advanced neoplasia (AN) after colonoscopy in individuals aged 40-49 years compared with that in individuals aged 50-59 years. A retrospective cohort study was performed among Kaiser Permanente Northern California members aged 40-59 years who had their first (index) colonoscopy in 2010-2013. Participants were followed up until death, disenrollment, AN on surveillance colonoscopy, or December 31, 2018. The risk for the development of AN was estimated using the Cox regression, adjusted for confounders. The study included 11,374 patients (2,396 aged 40-49 years and 8,978 aged 50-59 years). When comparing the 40-49 years group with the 50-59 years group, AN was detected in 2.2% vs 4.4% ( P = 0.0003) on surveillance colonoscopy after index colonoscopy finding of no adenoma, in 4.6% vs 7.0% ( P = 0.03) after a finding of nonadvanced adenoma (NAA), and in 7.9% vs 11.7% ( P = 0.06) after a finding of advanced adenoma (AA), respectively. Compared with the 50-59 years group, the 40-49 years group had a lower risk of metachronous AN when no adenoma was detected on index colonoscopy (hazard ratio [HR] 0.58; 95% confidence interval [CI] 0.39-0.83) and no difference when NAA (HR 0.84; 95% CI 0.54-1.24) or AA (HR 0.83; 95% CI 0.51-1.31) was detected. Compared with patients aged 50-59 years, patients aged 40-49 years may have a lower risk of developing metachronous AN when no adenoma is detected on index colonoscopy and a similar risk when NAA or AA is detected. These data suggest current surveillance colonoscopy guidelines may be applicable to patients aged 40-49 years who undergo colonoscopy.

Risk of Metachronous Colorectal Advanced Neoplasia and Cancer in Patients With 3-4 Nonadvanced Adenomas at Index Colonoscopy: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis evaluated the available evidence on the risk of metachronous advanced neoplasia (AN) and colorectal cancer (CRC) in patients with 3-4 nonadvanced adenomas (NAAs). We searched MEDLINE, EMBASE, and Cochrane Library databases up to January 2021 for studies evaluating metachronous AN and CRC risk by comparing 3 groups (1-2 vs 3-4 vs ≥5 NAAs) at index colonoscopy. The estimates for risk of metachronous AN and CRC were evaluated using random-effects models. Fifteen studies (n = 36,375) were included. The risk of metachronous AN was significantly higher in the 3-4 NAAs group than in the 1-2 NAAs group (relative risk [RR] 1.264, 95% confidence interval [CI] 1.053-1.518, P = 0.012; I2 = 0%); there was no difference between the ≥ 5 NAAs and 3-4 NAAs groups (RR 1.962, 95% CI 0.972-3.958, P = 0.060; I2 = 68%). The risks of metachronous CRC between the 1-2 NAAs and 3-4 NAAs groups (RR 2.663, 95% CI 0.391-18.128, P = 0.317; I2 = 0%) or the 3-4 NAAs and ≥ 5 NAAs groups (RR 1.148, 95% CI 0.142-9.290, P = 0.897; I2 = 0%) were not significantly different. Although the risk of metachronous AN was greater in the 3-4 NAAs group than in the 1-2 NAAs group, the risk of metachronous AN and CRC between the 3-4 NAAs and ≥ 5 NAAs groups was not different. This suggests that further studies on metachronous AN and CRC risk in the 3-4 NAAs group are warranted to confirm a firm ≥5-year interval surveillance colonoscopy.

The risk of advanced neoplasia after polypectomy of one to two non-advanced adenomas less than 5 mm in size vs. normal colonoscopy

BackgroundCurrent guidelines are inconsistent regarding the follow-up of patients with 1–2 diminutive (1–5 mm) non-advanced adenomas (DNAAs). AimsTo evaluate the risk of metachronous advanced neoplasia (AN), defined as cancer or advanced adenoma (AA), among patients with either normal colonoscopy or 1–2 DNAAs. MethodsA retrospective cohort study. Cohort I included 2,347 subjects with normal colonoscopy and 483 subjects with polypectomy of 1–2 DNAAs followed by colonoscopy. Cohort II included 11,881 subjects with normal colonoscopy and 1,342 subjects with 1–2 DNAAs followed through the cancer registry. ResultsIn cohort I, the rate of AN, cancer and AA among the polypectomy group vs. normal colonoscopy was 5.0% vs. 2.5%, Hazard Ratio (HR) 2.96 (95%CI [Confidence Interval]1.86–4.78) for AN; 0.6% vs. 0.3%, HR 3.32 (95%CI 0.85–13) for cancer; 4.3% vs. 2.2% HR 2.91 (95%CI 1.75–4.86) for AA. In cohort II, cancer occurred in 0.4% of the polypectomy group and 0.2% of the normal colonoscopy group, HR 2.27 (95% CI 0.56–9.19). ConclusionCompared to subjects with normal colonoscopy, subjects with polypectomy of 1–2 DNAAs, are at increased risk for AA when followed by colonoscopy, while the risk for cancer is non-significantly increased. Our findings suggest that patients with 1–2 DNNAs should be followed more tightly than patients with normal colonoscopy.

Prevalence of adenomatous polyposis in a fecal immunochemical test-based colorectal cancer screening program and risk of advanced neoplasia during follow-up.

We retrospectively included all FIT-positive participants with ≥ 10 adenomas at index colonoscopy between 2010 and 2018. Surveillance colonoscopies were collected until 2019. Patients with inherited syndromes, serrated polyposis syndrome, total colectomy, or lacking surveillance data were excluded. The cumulative incidence of CRC and advanced neoplasia were analyzed by Kaplan-Meier analysis. Risk factors for metachronous advanced neoplasia were investigated by multivariable logistic regression analysis. 215 of 9582 participants (2.2 %) had ≥ 10 adenomas. Germline genetic testing was performed in 92 % of patients with ≥ 20 adenomas, identifying two inherited syndromes (3.3 %). The 3-year cumulative incidence of CRC and advanced neoplasia were 1 % and 16 %, respectively. In 39 patients (24.2 %), no polyps were found on first surveillance colonoscopy. The presence of an advanced adenoma was independently associated with a higher risk of advanced neoplasia at first surveillance colonoscopy (odds ratio 3.91, 95 %CI 1.12-13.62; P = 0.03). Beyond the first surveillance colonoscopy, the risk of metachronous advanced neoplasia was lower. The prevalence of ≥ 10 adenomas in a FIT-based CRC screening program was 2.2 %; a small proportion of inherited syndromes were detected, even amongst those with ≥ 20 adenomas. A low rate of post-colonoscopy CRC was observed and the risk of advanced neoplasia beyond the first surveillance colonoscopy tended to progressively decrease throughout successive follow-ups.

Early-Onset Colorectal Cancer Is Associated with a Lower Risk of Metachronous Advanced Neoplasia than Traditional-Onset Colorectal Cancer.

Colorectal cancer (CRC) incidence in the USA has increased in adults under age 50. Current CRC surveillance guidelines do not consider age at diagnosis, and there are limited data available on outcomes from surveillance colonoscopies in early-onset CRC (EO-CRC) to guide recommendations on surveillance intervals. To compare surveillance outcomes between EO-CRC and traditional-onset colorectal cancer (TO-CRC). In a retrospective cohort study in a large tertiary care academic medical center, we collected data on patients with a diagnosis of CRC between 2000 and 2014 who received surgery with curative intent. We used log-rank test and inverse probability of treatment weighted Cox regression analysis to compare the development of metachronous advanced neoplasia (MAN) in patients with EO-CRC (diagnosed ages 18-49) and TO-CRC (diagnosed ages 50-75). Patients with EO-CRC (n = 107) were more likely to present with advanced-stage disease (62% versus 35%, p < 0.0001), rectal tumors (45% versus 27%, p < 0.01), and a family history of CRC (30% versus 16%, p = 0.02) compared to those with TO-CRC (n = 139). Patients with EO-CRC had lower risk of MAN (adjusted HR 0.44, 95% CI 0.22-0.88) than TO-CRC patients. The 5-year event rate for MAN was lower for patients with EO-CRC compared to patients with TO-CRC (5.8% vs. 16.1%, p = 0.07). The presence of synchronous neoplasia or history of diabetes was also predictive of MAN. EO-CRC was independently associated with a lower risk of developing MAN compared to TO-CRC. Shorter surveillance intervals may not be warranted in EO-CRC; however, large prospective studies are needed.

Risk Stratification Based on Synchronous Neoplasia and Clinical Physicochemical Characteristics Predicts a Higher Incidence of Metachronous Advanced Neoplasia in Patients Undergoing Colorectal Resection for Colorectal Cancer.

PurposePatients who undergo primary colorectal cancer (CRC) resection remain at increased risk for metachronous advanced neoplasia (MAN) in the remnant colorectum. This study aimed to investigate the incidence and clinicopathological characteristics predictive of MAN development in the residual colon after surgery.Patients and MethodsWe retrospectively reviewed 450 primary CRC cases referred to our hospital during a 4-year period. Univariate and multivariate analyses were performed to identify risk factors for MAN. The cumulative incidence of MAN was evaluated by the Cox proportional hazards model.ResultsMAN development was confirmed in 78 of the 450 patients (17.3%). Overall 1-, 2-, 3-, and 5-year cumulative probabilities were 0.9%, 4.8%, 9.8%, and 16.1%, respectively, for MAN. Among the clinical and colonoscopic factors at baseline, the independent factors that were significantly associated with MAN were synchronous neoplasia, carcinoembryonic antigen (CEA) level ≥10.0 ng/mL, and index cancer size ≥50 mm. The cumulative probability of MAN was significantly higher for patients with synchronous advanced neoplasia (SAN) than for those without synchronous neoplasia (P = 0.000). A subgroup analysis of patients based on the CEA level and index cancer size indicated that CEA ≥10 ng/mL and index cancer ≥50 mm resulted in a significantly higher cumulative probability of MAN (P = 0.039).ConclusionPatients with SAN or high preoperative serum CEA levels and large index cancer are at increased risk for early-onset MAN. More intensive surveillance strategies may be appropriate for these groups. Risk stratification based on synchronous neoplasia and clinical physicochemical characteristics requires further investigations involving modified appropriate postoperative colonoscopic surveillance schedules.

236 Young Adults With Adenomas: How Does Their Risk for Metachronous Advanced Adenomas Compare With Older Adults?

INTRODUCTION: Recent increases in colorectal cancer (CRC) incidence in adults less than 50 years of age have led to more colonoscopies in this age group. As a result, there is an increasing number of adults &lt;50 with adenomas detected. We used data from the New Hampshire Colonoscopy Registry (NHCR) to explore whether these younger adults with adenomas are at higher risk for future advanced findings than older patients, potentially requiring closer follow-up. METHODS: Our cohort was NHCR participants with at least one adenoma and/or serrated polyp on index exam and a follow-up colonoscopy at least 1 year after the index exam. Outcomes were the absolute and adjusted metachronous risks of advanced adenomas (AA: adenomas &gt;1 cm, with villous elements or high-grade dysplasia, or CRC) and large (&gt;1 cm) serrated polyps (SP). Incomplete exams and patients with IBD or genetic familial syndromes were excluded. We present absolute risk and adjusted risks from a logistic regression model stratified by age at index colonoscopy (&lt;40, 40–49, 50–59, and 60+ (ref)). Covariates include findings on previous and index colonoscopy, sex, smoking, body mass index (BMI), time to follow-up (months), bowel preparation quality, and family history of CRC. RESULTS: Time to follow-up did not vary with age in our sample of 10,116 adults (Table 1). Absolute risk for metachronous AA was lower for younger patients (P &lt; 0.0001) (Table 1), with the lowest risk in patients &lt;40, similar risks in the 40–49 and 50–59 groups, and highest risk in patients &gt;60. Adjusting for covariates did not change findings (P = 0.003). Because younger adults were less likely to have index AAs, we performed a sensitivity analysis, excluding index exams with AAs, and observed no changes in results (P = 0.003). The metachronous risk for large SPs was not significantly associated with age (Table 2). CONCLUSION: Younger adults with index adenomas have a lower risk for metachronous AAs than patients &gt;50. These data suggest that younger adults are not at higher risk for metachronous advanced neoplasia than older adults. The data also suggest that surveillance intervals recommended by current guidelines for adults &gt;50 years may be safe to apply to younger adults.

232 Numerous Non-Advanced Adenomas Are Not Associated With Metachronous Advanced Neoplasia

INTRODUCTION: Studies using standard definition colonoscopes in the early 2000s demonstrated the risk of metachronous advanced neoplasia (MAN) was doubled in patients with &gt;3 vs 1–2 small tubular adenomas. In the last decade, attention to the importance of adenoma detection rate and the use of high definition (HD) colonoscopes, increases small adenoma detection. We analyzed the association between baseline adenoma features, particularly multiplicity of non-advanced adenomas, on the risk of MAN in patients undergoing HD colonoscopy. METHODS: Patients undergoing first colonoscopy at age ≥50 in the era of HD colonoscopes (≥2006) and follow-up colonoscopy &gt;24 months from baseline exam were identified from the electronic medical record. Exclusions included inflammatory bowel disease, history of colorectal cancer or colon surgery, incomplete colonoscopy, and inadequate bowel preparation. High risk adenoma (HRA) patients included those with an advanced adenoma (≥10 mm in size, adenoma with villous features/high-grade dysplasia) or ≥3 adenomas. Low risk adenoma (LRA) patients included those with 1–2, &lt;10 mm tubular adenomas. The risk of MAN was calculated according to baseline adenoma features. Multivariable analysis compared the risk of MAN between individuals with LRA vs HRA on baseline HD colonoscopy adjusted for interval between first and follow-up colonoscopies. RESULTS: 159,273 patients underwent colonoscopy at age ≥50 in 2006 or later. After exclusions, 3,383 were included. Mean age was 60.5 ± 7.8 and 54.6% were females. The median time interval between the first and follow-up colonoscopy was 59.9 (42.5–66.7) months for the LRA group and 41.8 (36.3–52.2) months for the HRA group. The risk of MAN was 3.8% in individuals with no baseline adenomas; 4% with LRA; and 9.2% with HRA. The risk of MAN in individuals with &gt;3 non-advanced adenomas was 6.3%; 6.1% with 3–4 and 7.4% with &gt;5 non-advanced adenomas (Table 1). On multivariable analysis, the risk of MAN was not different between HRA and LRA based upon the number of non-advanced adenomas: &gt;3 [OR 1.6, (0.7, 3.9)]; 3–4 [OR 1.6, (0.61, 4.0)] and &gt;5 non-advanced adenomas [OR 2.2, (0.27, 17.0)] (Table 2). CONCLUSION: In the contemporary era of HD colonoscopy, compared to LRA patients, patients with ≥3 non-advanced adenomas are not at increased risk of MAN including patients with 3–4 and ≥5 non-advanced adenomas. These data support a longer colonoscopy interval (&gt;5 years) in these individuals.

The predictive value of small versus diminutive adenomas for subsequent advanced neoplasia

Patients with previous colorectal adenomas are at increased risk of colorectal cancer. Current guidelines for postpolypectomy surveillance intervals treat all tubular adenomas 1 to 9mm in size with low-grade dysplasia as carrying the same level of risk. We evaluated whether 6 to 9mm adenomas detected at colonoscopy are associated with greater risk of advanced neoplasia at follow-up compared with baseline 1 to 5mm adenomas. We retrospectively evaluated a colonoscopy database at a single U.S. academic center. Patients with baseline examinations demonstrating tubular adenomas 1 to 9mm in size with low-grade dysplasia and no advanced adenomas were included. Follow-up colonoscopies were performed at least 200 days later and were assessed for incident advanced neoplasia (cancer, high-grade dysplasia, adenoma≥10mm in size, or villous elements). There were 2477 qualifying baseline colonoscopies. The absolute risk of metachronous advanced neoplasia increased from 3.6% in patients with 1 to 5mm adenomas to 6.9% in patients with at least 1 adenoma of 6 to 9mm (P= .001). Patients with 5 or more adenomas 1 of which was at least 6 to 9mm had the highest risk of advanced neoplasia at follow-up (10.4%, P= .006). When only screening colonoscopies were considered, all baseline groups (1-2 adenomas, 3-4 adenomas,≥5 adenomas) with adenomas 6 to 9mm in size had an increased risk for metachronous advanced neoplasia (odds ratio [OR], 4.07; 95% confidence interval [CI], 1.50-11.04; OR, 4.91; 95% CI, 1.44-16.75; OR, 4.71; 95% CI, 1.30-17.05, respectively). Patients with baseline small (6-9mm) adenomas have an increased risk of advanced lesions on follow-up compared with patients with only diminutive (1-5mm) adenomas. Postpolypectomy guidelines should consider risk stratification based on small versus diminutive adenomas.

Diminutive Polyps With Advanced Histologic Features Do Not Increase Risk for Metachronous Advanced Colon Neoplasia

With advances in endoscopic imaging, it is possible to differentiate adenomatous from hyperplastic diminutive (1-5 mm) polyps during endoscopy. With the optical Resect-and-Discard strategy, these polyps are then removed and discarded without histopathology assessment. However, failure to recognize adenomas (vs hyperplastic polyps), or discarding a polyp with advanced histologic features, could result in a patient being considered at low risk for metachronous advanced neoplasia, resulting in an inappropriately long surveillance interval. We collected data from international cohorts of patients undergoing colonoscopy to determine what proportion of patients are high risk because of diminutive polyps advanced histologic features and their risk for metachronous advanced neoplasia. We collected data from 12 cohorts (in the United States or Europe) of patients undergoing colonoscopy after a positive result from a fecal immunochemical test (FIT cohort, n= 34,221) or undergoing colonoscopies for screening, surveillance, or evaluation of symptoms (colonoscopy cohort, n= 30,123). Patients at high risk for metachronous advanced neoplasia were defined as patients with polyps that had advanced histologic features (cancer, high-grade dysplasia, ≥25% villous features), 3 or more diminutive or small (6-9 mm) nonadvanced adenomas, oran adenoma or sessile serrated lesion ≥10 mm. Using an inverse variance random effects model, we calculated the proportion of diminutive polyps with advanced histologic features; the proportion of patients classified as high risk because their diminutive polyps had advanced histologic features; and the risk of these patients for metachronous advanced neoplasia. In 51,510 diminutive polyps, advanced histologic features were observed in 7.1% of polyps from the FIT cohort and 1.5% polyps from the colonoscopy cohort (P= .044); however, this difference in prevalence did not produce a significant difference in the proportions of patients assigned to high-risk status (0.8% of patients in the FIT cohort and0.4% of patients in the colonoscopy cohort) (P= .25). Theproportions of high-risk patients because of diminutive polyps with advanced histologic features who were found tohave metachronous advanced neoplasia (17.6%) did not differ significantly from the proportion of low-risk patients with metachronous advanced neoplasia (14.6%) (relative risk for high-risk categorization, 1.13; 95% confidence interval 0.79-1.61). In a pooled analysis of data from 12 international cohorts of patients undergoing colonoscopy for screening, surveillance, or evaluation of symptoms, we found that diminutive polyps with advanced histologic features do not increase risk for metachronous advanced neoplasia.

Risk of Metachronous Advanced Neoplasia in Patients With Multiple Diminutive Adenomas

Individuals with advanced adenomas or three or more adenomas have a higher risk of metachronous advanced neoplasia (AN) and are recommended to undergo surveillance colonoscopy at shorter intervals. However, it is questionable whether patients with multiple (three or more) non-advanced diminutive adenomas should be considered as high-risk. We analyzed 5482 patients diagnosed with one or more adenomas during their first colonoscopy screening and who underwent a follow-up colonoscopy. Patients were categorized into four groups based on adenoma characteristics at baseline: Group 1, 1-2 non-advanced adenomas; Group 2, ≥3 non-advanced, diminutive (1 to 5 mm) adenomas; Group 3, ≥3 non-advanced, small (6-9 mm) adenomas; and Group 4, advanced adenomas. During a median follow-up of 38 months, the incidence of metachronous AN at surveillance colonoscopy was 5.6%. The incidence of AN was 3.9% in group 1, 5.9% in group 2, 10.6% in group 3, and 22.1% in group 4. The adjusted hazard ratios (HRs) [95% confidence intervals (CIs)] for metachronous AN between group 2, group 3, and group 4, and low risk group 1 were 1.71 (0.99-2.94), 2.76 (1.72-4.44), and 5.23 (3.57-7.68), respectively. Compared with group 4, the adjusted HRs (95% CIs) for group 1, group 2, and group 3 were 0.19 (0.13-0.28), 0.32 (0.18-0.59), and 0.52 (0.31-0.89), respectively. We found that patients with three or more non-advanced diminutive adenomas had a borderline increased risk of metachronous AN compared with patients with low risk adenomas.

Can the Sum of Adenoma Diameters (Adenoma Bulk) on Index Examination Predict Risk of Metachronous Advanced Neoplasia?

Recent data suggest that adenoma size and number are more important predictors of metachronous colorectal neoplasia than advanced histology. Furthermore, there is poor reproducibility in diagnosing advanced histology; high-grade dysplasia and villous histology. Therefore we developed a new metric, adenoma bulk, the sum of diameters of all baseline adenomas, regardless of advanced features. Compare the predictive value for metachronous advanced neoplasia of adenoma bulk to conventional paradigm. Data were collected prospectively in a multicenter adenoma-chemoprevention trial (2004 to 2013). For the conventional paradigm, high-risk baseline findings were defined as ≥3 adenomas, large adenomas (≥1 cm) or adenomas with villous components or high-grade dysplasia. Adenoma bulk was examined across quartiles and as a continuous variable. Predictive characteristics (sensitivities, specificities, c-statistics) for metachronous advanced neoplasia using conventional criteria and adenoma bulk were calculated. receiver operator characteristic curves were computed using logistic regression. In total, 1948 adults had index and follow-up colonoscopies (mean follow-up, 45.2 mo). Those with an adenoma bulk ≥10 mm (4th quartile) had a higher metachronous advanced neoplasia risk (14.4% vs. 6.9-8.2% in lower 3 quartiles; P=0.0002). The c-statistics and sensitivities (specificity fixed at 0.73) for the adenoma bulk and conventional models were 0.587 and 0.563 (P=0.17) and 0.396 and 0.390, respectively. Categorizing sporadic adenoma patients as high versus low risk for metachronous advanced neoplasia by adenoma bulk of <versus ≥10 mm may be comparably predictive as conventional paradigm and simplifies risk stratification by obviating need for additional histology regarding extent of villous component or degree of dysplasia in resected polyps. The adenoma bulk metric and the 10 mm cutoff in particular would have to be validated in other populations before it can be used in clinical practice.

Higher incidence of metachronous advanced neoplasia in patients with synchronous advanced neoplasia and left-sided colorectal resection for colorectal cancer

There is an increased risk of developing metachronous colorectal cancer (CRC) in the remnant colorectum after surgical resection of CRC. We evaluated the incidence of metachronous advanced neoplasia (AN) after surgery for CRC according to resection type and synchronous AN. This cohort study included patients who underwent surgical resection for initial CRC at a tertiary cancer center in Japan between September 2002 and December 2012. The cumulative probability of metachronous AN was calculated using the Kaplan-Meier method and was evaluated by the log-rank test. Metachronous AN was detected in 145 of 1731 included patients, and the 5-year cumulative probability of metachronous AN was 13.1%. There was no significant difference in the incidence of metachronous AN in the right-sided colorectal resection versus left-sided colorectal resection (LCR) groups (log-rank test P= .151), whereas the incidence of metachronous AN was significantly higher in patients with synchronous AN (log-rank test P< .001). In subgroup analysis of patients according to resection type and synchronous AN, the LCR groupwith synchronous AN showed a significantly higher incidence of metachronous AN than the other groups (log-rank test P< .001). We found that synchronous AN, but not resection type, was independently associated with the incidence of metachronous AN in patients who underwent surgical resection of CRC. In addition, subjects with synchronous AN after LCR had a potentially increased risk for metachronous AN. Thus, it may be useful to perform risk stratification according to synchronous AN and resection type.