P188 Cumulative inflammatory burden as a risk factor for colorectal neoplasia in inflammatory bowel disease patients with primary sclerosing cholangitis: a multi-center case-control study

Abstract

Abstract Background Inflammatory bowel disease (IBD) patients with concomitant primary sclerosing cholangitis (PSC-IBD) have a 25-year cumulative risk of up to 50% to develop colorectal neoplasia (CRN). Mucosal inflammation is an important driver of CRN, but it is unknown whether this also applies to PSC-IBD patients. We aimed to assess the impact of chronic mucosal inflammation per colonic segment on CRN risk in PSC-IBD patients. Methods This is a multi-center case-control study including cases with PSC-IBD and CRN and controls with PSC-IBD without CRN. Subjects were included from 8 medical centers in Canada and the Netherlands. Exclusion criteria were a CRN diagnosis prior to IBD or PSC diagnosis, familial CRC syndromes, and <2 available colonoscopy reports. Data was collected on demographics, IBD and PSC disease characteristics, CRN lesions, and endoscopy reports between 1977 and 2023. Pan-colonic and segmental (right colon, transverse colon, left colon, rectum) endoscopic cumulative inflammatory burden scores were calculated as the sum of (mean) endoscopic inflammation severity between colonoscopies x length of the surveillance interval until index procedure. The index procedure was the colonoscopy during which CRN was detected (cases) or randomly selected and matched for disease duration (controls). The primary outcome was a CRN diagnosis, secondary outcomes were CRN grade and location, time to CRN (Kaplan-Meier curve), pan-colonic cumulative inflammatory burden, cumulative inflammatory burden per colonic segment harboring CRN, and colonic surgery. Results We included 335 PSC-IBD patients (224 UC, 101 CD) with a median follow-up of 8 years (IQR: 5.0-14.0) and 6 endoscopies (IQR: 4.0-8.0). Median disease duration was 19.5 years for IBD (IQR: 11.0-26.0) and 13 years for PSC (IQR: 7.0-19.0). Advanced neoplasia (HGD or CRC) was found in 35 out of 102 cases (34%). Fifty-six (55%) cases were diagnosed with > 1 lesion, and 43 (42%) had ≥ 1 right-sided lesion. Median time to index CRN was 17 years (IQR: 8.0-24.0). Sixty-six patients underwent (sub)total colectomy or proctocolectomy, including 49 (74%) due to CRN diagnosis. There was no difference in pan-colonic cumulative inflammatory burden scores (mean scores: 4.7 (cases) and 3.7 (controls); P=0.21, 95%-CI: -2.52-.56) and segmental scores (mean scores: 4.9 (cases) and 4.1 (controls); P=0.27, 95%-CI: -2.29-.65) between cases and controls. Mortality was 13% (n=45.) Conclusion In this large multi-center cohort study, the risk for CRN-associated colectomy in PSC-IBD was high, while pan-colonic and segmental cumulative inflammatory burden scores were not associated with CRN risk.