Low Colorectal Cancer Risk After Resection of High-Risk Pedunculated Polyps

Abstract

IntroductionPost-Faecal Immunochemical Test (FIT) colonoscopy represents a setting with an enriched prevalence of advanced adenomas. Due to an expected higher risk of Colorectal Cancer (CRC), post-polypectomy surveillance is recommended, generating a substantially increased load on endoscopy services. The aim of our study was to investigate post-polypectomy CRC risk in a screening population of FIT+ subjects after resection of low- (LRA) or high-risk adenomas (HRA). MethodsWe retrieved data from a cohort of patients undergoing post-polypectomy surveillance within a FIT-based CRC screening program in Italy between 2002 and 2017 and followed-up to December 2021. Main outcomes were post-polypectomy CRC incidence and mortality risks according to type of adenoma (LRA/HRA) removed at colonoscopy as well as morphology, size, dysplasia and location of the index lesion. We adopted as comparators FIT+/colonoscopy negative and FIT negative patients. The absolute risk was calculated as the number of incident CRCs per 100,000 person-years of follow-up. We used Cox multivariable regression models to identify associations between CRC risks and patient- and polyp-related variables. ResultsOverall, we included 87,248 post-FIT+ colonoscopies (133 endoscopists). Of these, 42,899 (49.2%) were negative, 21,650 (24.8%) had a LRA and 22,709 (26.0%) a HRA. After a median follow-up of 7.25 years, a total of 635 CRCs were observed. For patients with LRAs, CRC incidence (Hazard Ratio [HR] 1.18, 95% Confidence Interval [CI] 0.92-1.53) was not increased compared to the FIT+/colonoscopy negative group, while for HRAs a significant increase in CRC incidence (HR 1.53, 95% CI 1.14-2.04) was found. The presence of one or more risk factors among proximal location, non-pedunculated morphology and high-grade dysplasia explained most of this excess CRC risk in the HRA group (HR 1.85, 95% CI 1.36-2.52). Patients with only distal pedunculated polyps without HGD, representing 39.2% of HRA, did not have increased risk compared to the FIT-negative group (HR 0.87, 95% CI 0.59 - 1.28). ConclusionsCRC incidence is significantly higher in patients with high-risk adenomas diagnosed at colonoscopy. However, such excess risk does not appear to apply to patients with only distal pedunculated polyps without HGD, an observation that could potentially reducethe burden of surveillance in FIT programs.