Background and study aims: Post-colonoscopy colorectal cancers (PCCRCs) may account for up to 50% of all colorectal cancers (CRCs) diagnosed in patients with inflammatory bowel disease (IBD). This may reflect a high colonoscopy frequency; however evidence remains limited.
Patient and methods: We conducted a cohort study of IBD and non-IBD patients undergoing colonoscopy. We calculated 6-36 months CIPs of PCCRC after first-time and subsequent colonoscopies. We also computed crude and adjusted HRs of PCCRC, comparing IBD with non-IBD patients undergoing first-time and subsequent colonoscopies. Separate analyses were conducted for consecutive colonoscopies. We calculated PCCRC-3 year rates to estimate the proportion of IBD and non-IBD CRC patients experiencing PCCRC.
Results: We observed 138 and 1,909 PCCRCs among 34,688 IBD and 358,217 non-IBD patients who underwent colonoscopy. The CIP of PCCRC after first-time colonoscopy was 0.21%, 95% confidence interval (CI): [0.17-0.27] for IBD patients and 0.37%, 95% CI: [0.35-0.39] for non-IBD patients. The adjusted HR of PCCRC after a first-time colonoscopy was 0.96, 95% CI: [0.75-1.22] and the adjusted HRs after subsequent colonoscopies had point estimates around 1.0. The PCCRC-3 year rate was 24.3%, 95% CI: [20.4-28.7] for IBD and 7.5%, 95% CI [7.2-7.8] for non-IBD patients.
Conclusions: Although PCCRCs accounted for a substantial proportion of all IBD-related CRCs, IBD patients had a low CIP of PCCRC after colonoscopy. The elevated PCCRC-3 year rates may among other factors stem from increased colonoscopy frequency in IBD patients.
Incidence and Classification of Postcolonoscopy Colorectal Cancers in Inflammatory Bowel Disease: A Dutch Population-Based Cohort Study