RISK FACTORS FOR METACHRONOUS COLORECTAL CANCER OR ADVANCED LESIONS AFTER ENDOSCOPIC RESECTION OF SERRATED POLYPS: A SYSTEMATIC REVIEW AND META-ANALYSIS.

BACKGROUND AND AIMS: Serrated polyps (SPs) are precursors to 15-20% of colorectal cancers (CRCs). However, there are uncertainties regarding which SPs require surveillance and at what intervals, with recommendations adapted from those for adenomas in the absence of solid evidence. Our aim was to assess which SP risk characteristics relate to a higher risk of metachronous CRC or advanced polyps. METHODS: We systematically searched PubMed, EMBASE, and Cochrane for cohort, case-control studies, and clinical trials from inception to Dec 31, 2023, for CRC or advanced polyps [advanced adenoma (AA) or advanced SP] incidence at surveillance stratified by baseline SP size, dysplasia, location, and multiplicity. We defined advanced SPs as those >10mm or with dysplasia. CRC and advanced polyp incidence per 1,000 person-years (p-y) were estimated. We performed a meta-analysis by calculating pooled relative risks (RR) using a random-effects model. RESULTS: 5,903 studies were reviewed and 14 included, with 493,949 patients (mean age 59·5 years, 55% men). Mean follow-up was 4·9 years. CRC incidence per 1,000 p-y was 2·09 (95%CI 1·29-2·90) for advanced SP, 1·52 (0·78-2·25) for SP>10mm, 5·86 (2·16-9·56) for SP with dysplasia, 1·18 (0·77-1·60) for proximal SP, 0·52 (0·08-1·12) for >3SP, 0·50 (0·35-0·66) for non-advanced SP, and 0·44 (0·41-0·46) for normal colonoscopy. Metachronous CRC risk was higher in advanced SP vs non-advanced SP (RR 1·84, 95%CI 1·11-3·04), and vs normal colonoscopy (RR 2·92, 2·26-3·77); in SP>10mm vs <10mm (RR 2·61, 1·43-4·77), and vs normal colonoscopy (RR 3·52, 2·17-5·69); and in SP with dysplasia vs normal colonoscopy (RR 2·71, 2·00-3·67). No increase in CRC or advanced polyp risk was found in patients with proximal vs distal SP, nor in >3SP vs 1-2SP. CONCLUSIONS: CRC risk is significantly higher in patients with baseline advanced SP after 4·9 years of follow-up, with risk magnitudes similar to those described for AA, supporting the current recommendation for 3-year surveillance in patients with advanced SP.

Role of Artificial Intelligence in Colonoscopy Detection of Advanced Neoplasias : A Randomized Trial.

BACKGROUND: The role of computer-aided detection in identifying advanced colorectal neoplasia is unknown. OBJECTIVE: To evaluate the contribution of computer-aided detection to colonoscopic detection of advanced colorectal neoplasias as well as adenomas, serrated polyps, and nonpolypoid and right-sided lesions. DESIGN: Multicenter, parallel, randomized controlled trial. (ClinicalTrials.gov: NCT04673136). SETTING: Spanish colorectal cancer screening program. PARTICIPANTS: 3213 persons with a positive fecal immunochemical test. INTERVENTION: Enrollees were randomly assigned to colonoscopy with or without computer-aided detection. MEASUREMENTS: Advanced colorectal neoplasia was defined as advanced adenoma and/or advanced serrated polyp. RESULTS: The 2 comparison groups showed no significant difference in advanced colorectal neoplasia detection rate (34.8% with intervention vs. 34.6% for controls; adjusted risk ratio [aRR], 1.01 [95% CI, 0.92 to 1.10]) or the mean number of advanced colorectal neoplasias detected per colonoscopy (0.54 [SD, 0.95] with intervention vs. 0.52 [SD, 0.95] for controls; adjusted rate ratio, 1.04 [99.9% CI, 0.88 to 1.22]). Adenoma detection rate also did not differ (64.2% with intervention vs. 62.0% for controls; aRR, 1.06 [99.9% CI, 0.91 to 1.23]). Computer-aided detection increased the mean number of nonpolypoid lesions (0.56 [SD, 1.25] vs. 0.47 [SD, 1.18] for controls; adjusted rate ratio, 1.19 [99.9% CI, 1.01 to 1.41]), proximal adenomas (0.94 [SD, 1.62] vs. 0.81 [SD, 1.52] for controls; adjusted rate ratio, 1.17 [99.9% CI, 1.03 to 1.33]), and lesions of 5 mm or smaller (polyps in general and adenomas and serrated lesions in particular) detected per colonoscopy. LIMITATIONS: The high adenoma detection rate in the control group may limit the generalizability of the findings to endoscopists with low detection rates. CONCLUSION: Computer-aided detection did not improve colonoscopic identification of advanced colorectal neoplasias. PRIMARY FUNDING SOURCE: Medtronic.

Risk Factors for Metachronous Colorectal Cancer or Advanced Adenomas After Endoscopic Resection of High-risk Adenomas.

BACKGROUND & AIMS: Among the characteristics of high-risk adenomas (HRAs), some may predict a higher risk of metachronous advanced lesions. Our aim was to assess which HRA characteristics are associated with high risk of metachronous colorectal cancer (CRC) or advanced adenomas (AAs). METHODS: We systematically searched Pubmed, EMBASE, and Cochrane for cohort studies and clinical trials of CRC or AA incidence at surveillance stratified by baseline lesion size, histology, and multiplicity. We calculated pooled relative risks (RRs) using a random-effects model. Heterogeneity was assessed with the I2 statistic. RESULTS: Fifty-five studies were included, with 936,540 patients with mean follow-up 5.4 ± 2.9 years. CRC incidence per 1000 person-years was 2.6 (2.1-3.0) for adenomas ≥20 mm, 2.7 (2.2-3.2) for high-grade dysplasia (HGD), 2.0 (1.8-2.3) for villous component, 0.8 (0.1-1.4) for ≥5 adenomas, 1.0 (0.7-1.2) for ≥3 adenomas. Metachronous CRC risk was higher in adenomas ≥20 mm vs 10 to 19 mm (RR, 2.08; 95% confidence interval [CI], 1.20-3.61), HGD vs low-grade dysplasia (RR, 2.89; 95% CI, 1.88-4.44), villous vs tubular (RR, 1.75; 95% CI, 1.33-2.31). No significant differences in CRC risk were found in ≥3 adenomas vs 1 to 2 (RR, 1.24; 95% CI, 0.84-1.83), nor in ≥5 adenomas vs 3 to 4 (RR, 0.79; 95% CI, 0.30-2.11). Compared with normal colonoscopy, RR for CRC risk was 2.61 (95% CI, 2.06-3.32) for ≥10mm, 6.62 (95% CI, 4.60-9.52) for HGD, 3.58 (95% CI, 2.24-5.73) for villous component, and 2.03 (95% CI, 1.40-2.94) for ≥3 adenomas. Similar trends were seen for metachronous AAs. CONCLUSION: Metachronous CRC risk is highest in patients with baseline adenomas with ≥20 mm or HGD. Multiplicity does not seem to be associated with substantially higher CRC risk in the near term.

Incidence, characteristics, and predictive factors of post-colonoscopy colorectal cancer.

BACKGROUND: Post-colonoscopy colorectal cancer (PCCRC) is colorectal cancer (CRC) diagnosed after a colonoscopy in which no cancer is found. OBJECTIVE: As PCCRC has become an important quality indicator, we determined its rates, characteristics, and index colonoscopy-related predictive factors. METHODS: We carried out a multicenter, observational, retrospective study between 2015 and 2018. Rates were calculated for PCCRC developing up to 10 years after colonoscopy. PCCRC was categorized according to the most plausible explanation using World Endoscopy Organization methodology. Our PCCRC population was compared to a control cohort without CRC matched 1:4 by sex, age, index colonoscopy date, indication, endoscopist, and hospital. RESULTS: One hundred seven PCCRC and 2508 detected CRC were diagnosed among 101,524 colonoscopy (0.1%), leading to rates of 0.4%, 2.2%, 3.1%, and 4.1% at 1, 3, 5, and 10 years, respectively. PCCRC was in right (42.4%), left (41.4%), and transverse (16.4%) colon with 31.5% at stage I, 24.7% stage II, 32.6% stage III, and 11.2% stage IV. Twenty point three percent were classified as incomplete resection, 5.4% as unresected lesions, 48.6% as missed lesions with adequate colonoscopy, and 25.7% as missed lesions with inadequate colonoscopy. The median time from colonoscopy to PCCRC was 42 months. Previous inadequate preparation (OR 3.05, 95%CI 1.73-5.36) and piecemeal polypectomy (OR 19.89, 95%CI 8.67-45.61) were independently associated with PCCRC. CONCLUSIONS: In our population, 4.1% of CRC cases were PCCRC. Most of these lesions were in right colon and attributable to lesions not visualized despite adequate bowel cleansing. Previous inadequate cleansing and piecemeal polypectomy were associated with PCCRC.

Effect of the SARS-CoV-2 pandemic on colorectal cancer diagnosis and prognosis.

BACKGROUND AND STUDY AIMS: Our aim was to determine the impact of the SARS-CoV-2 pandemic on the diagnosis and prognosis of colorectal cancer (CRC). PATIENTS AND METHODS: This prospective cohort study included individuals diagnosed with CRC between March 13, 2019 and June 20, 2021 across 21 Spanish hospitals. Two time periods were compared: prepandemic (from March 13, 2019 to March 13, 2020) and pandemic (from March 14, 2020 to June 20, 2021, lockdown period and 1 year after lockdown). RESULTS: We observed a 46.9% decrease in the number of CRC diagnoses (95% confidence interval (CI): 45.1%-48.7%) during the lockdown and 29.7% decrease (95% CI: 28.1%-31.4%) in the year after the lockdown. The proportion of patients diagnosed at stage I significantly decreased during the pandemic (21.7% vs. 19.0%; p = 0.025). Centers that applied universal preprocedure SARS-CoV-2 PCR testing experienced a higher reduction in the number of colonoscopies performed during the pandemic post-lockdown (34.0% reduction; 95% CI: 33.6%-34.4% vs. 13.7; 95% CI: 13.4%-13.9%) and in the number of CRCs diagnosed (34.1% reduction; 95% CI: 31.4%-36.8% vs. 26.7%; 95% CI: 24.6%-28.8%). Curative treatment was received by 87.5% of patients diagnosed with rectal cancer prepandemic and 80.7% of patients during the pandemic post-lockdown period (p = 0.002). CONCLUSIONS: The COVID-19 pandemic has led to a decrease in the number of diagnosed CRC cases and in the proportion of stage I CRC. The reduction in the number of colonoscopies and CRC diagnoses was higher in centers that applied universal SARS-CoV-2 PCR screening before colonoscopy. In addition, the COVID-19 pandemic has affected curative treatment of rectal cancers.