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

ABSTRACT

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.