To Örebro University

BACKGROUND: Inflammatory bowel disease (IBD) has been linked to an increased risk of colorectal neoplasia. However, the types and risks of specific polyp types in IBD are less clear.

METHODS: We identified 41,880 individuals with IBD [Crohn's disease (CD: n=12,850); Ulcerative colitis (UC): n=29,030)] from Sweden matched with 41,880 reference individuals. Using Cox regression, we calculated adjusted hazard ratios (aHRs) for neoplastic colorectal polyps (Tubular, Serrated/Sessile, Advanced and Villous) defined by histopathology codes.

RESULTS: During follow-up, 1648 (3.9%) IBD patients and 1143 (2.7%) reference individuals had an incident neoplastic colorectal polyp, corresponding to an incidence rate of 46.1 and 34.2 per 10,000 person-years, respectively. This correlated to an aHR of 1.23 (95% CI 1.12-1.35) with the highest HRs seen for sessile serrated polyps (8.50, 95% CI 1.10-65.90) and traditional serrated adenomas (1.72, 95% CI 1.02-2.91). aHRs for colorectal polyps were particularly elevated in those diagnosed with IBD at a young age and after 10 years after diagnosis. Both absolute and relative risks of colorectal polyps were higher in UC than in CD (aHRs 1.31 vs. 1.06, respectively), with a 20-year cumulative risk differences of 4.4% in UC and 1.5% in CD, corresponding to one extra polyp in 23 patients with UC and one in 67 CD patients during the first 20 years after IBD diagnosis.

CONCLUSIONS: In this nationwide population-based study, there was an increased risk of neoplastic colorectal polyps in IBD patients. Colonoscopic surveillance in IBD appears important, especially in UC and after 10 years of disease.