Preventable Predictive Factors of Post-colonoscopy Colorectal Cancer in Inflammatory Bowel Disease.

Background and aim: Post-colonoscopy colorectal cancer [PCCRC] is a colorectal cancer [CRC] diagnosed after a colonoscopy in which no cancer was detected [index colonoscopy]. Although the overall cumulative rates of PCCRC are low in both the general population and inflammatory bowel disease [IBD] patients, the overall incidence of PCCRC in IBD is greater than that documented in the general population. This study aimed to identify the index colonoscopy-related factors and patients' characteristics influencing IBD-associated PCCRC development.

Methods: We carried out an observational, retrospective study in which IBD-associated PCCRCs were diagnosed between 2010 and 2023. The PCCRC group was compared with a control cohort of IBD patients without CRC, matched 1:1 by several demographic and clinical features as well as characteristics of index colonoscopy, to minimise selection bias.

Results: Among 61 CRCs identified, 37 [61%] were PCCRC. Twelve of the 37 [32%] PCCRC were diagnosed within 12 months after the previous negative colonoscopy, 15 [41%] within 12-36 months, and 10 [27%] within 36-60 months. In the multivariate analysis, the inadequate bowel preparation of the index colonoscopy (odds ratio [OR]: 5.9; 95% confidence interval [CI]: 11.1-31.4) and the presence of high-risk factors for CRC [OR: 24.03; 95% CI: 3.1-187.8] were independently associated with PCCRC. Conversely, prior exposure to immunosuppressors or biologics [OR: 0.17; 95% CI: 0.03-0.83] and random biopsies sampling at index colonoscopy [OR: 0.19; 95% CI: 0.04-0.85] were inversely associated with PCCRC.

Conclusions: More than 50% of CRCs in our population were PCCRC. PCCRCs were associated with previous inadequate cleansing and occurred more frequently in high-risk patients.