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

Introduction: The risk of total metachronous advanced neoplasia (TMAN) in patients with serrated lesions (SL) and IBD is unknown. Study aim was to compare the risk of TMAN at surveillance colonoscopies in patients with SL and IBD to patients with SL without IBD. We also sought to compare IBD severity in patients with IBD and SL in a colonic area involved with IBD (SL-IA) to patients with IBD and SL in an uninvolved area (SL-UA). Methods: A retrospective cohort study was conducted. Through pathology database search, we identified 2428 patients with endoscopically resected SL, defined as sessile serrated lesion (SSL), traditional serrated adenoma (TSA) or IBD and serrated epithelial change (SEC), between 2010 and 2019 at the University of Montreal Hospital Center. We included patients aged 45-75 without polyposis syndromes and excluded patients with a history of CRC, first surveillance < 12 months after complete index, sigmoidoscopy, or no follow-up. Patient files were reviewed for demographic data, IBD severity, and findings at index and follow-up. Follow-up was continued until TMAN or last colonoscopy within 10 years. Primary outcome was the risk of TMAN (defined as advanced adenoma (AA), advanced serrated lesion (ASL) or CRC) in a surveillance colonoscopy within 10 years from index. We performed univariate and multivariate Cox regressions. Results: In the metachronous outcomes analysis, 440 patients with SL (mean age 61.8 y., 51.6% male, 424 SSL, 16 TSA) were eligible, and 37 with SL and IBD were eligible (mean age 60.9 y., 54.1% male, 30 SSL, 6 SEC, 1 TSA). Compared to patients without IBD, patients with IBD had a similar risk of metachronous TMAN (HR=0.92 [0.44–1.90]), AA (HR=0.53 [0.13–2.12]) and ASL (HR=1.03 [0.44–2.41]). In the comparison of SL-UA and SL-IA, 56 patients with IBD were eligible, with 21 having SL-UA (mean age 62.0 y., 42.9% male, 19 SSL, 1 TSA, 1 SEC) and 35 having SL-IA (mean age 60.8 y., 62.9% male, 27 SSL, 1 TSA and 8 SEC). Both groups had similar intervals between IBD diagnosis and SL diagnosis (P >0.05), and maximal therapeutic maintenance steps (P >0.05), as well as Mayo/SES-CD scores, serum C-reactive protein, hemoglobin, and albumin, and fecal calprotectin values at index and last colonoscopy (P >0.05). Conclusion: Patients with SL and IBD are not at higher risk of total metachronous advanced neoplasia than patients with SL and no IBD. SLs in IBD should be considered sporadic and undergo endoscopic resection and follow-up similar to non-IBD patients.