The risk of inflammatory bowel disease-related colorectal carcinoma is limited: results from a nationwide nested case-control study.

OBJECTIVES: The risk for inflammatory bowel disease (IBD)-related colorectal cancer (CRC) remains a matter of debate. Initial reports mainly originate from tertiary referral centers, and conflict with more recent studies. Overall, epidemiology of IBD-related CRC is relevant to strengthen the basis of surveillance guidelines. We performed a nationwide nested case-control study to assess the risk for IBD-related CRC and associated prognostic factors in general hospitals.

METHODS: IBD patients diagnosed with CRC between January 1990 and July 2006 in 78 Dutch general hospitals were identified as cases, using a nationwide automated pathology database. Control IBD patients without CRC were randomly selected. Clinical data were collected from detailed chart review. Poisson regression analysis was used for univariable and multivariable analyses.

RESULTS: A total of 173 cases were identified through pathology and chart review and compared with 393 controls. The incidence rate of IBD-related CRC was 0.04%. Risk factors for IBD-related CRC were older age, concomitant primary sclerosing cholangitis (PSC, relative ratio (RR) per year duration 1.05; 95% confidence interval (CI) 1.01-1.10), pseudopolyps (RR 1.92; 95% CI 1.28-2.88), and duration of IBD (RR per year 1.04; 95% CI 1.02-1.05). Using immunosuppressive therapy (odds ratio (OR) 0.3; 95% CI 0.16-0.56, P<0.001) or anti-tumor necrosis factor (TNF) (OR 0.09; 95% CI 0.01-0.68, P<0.02) was protective.

CONCLUSIONS: We found a limited risk for developing IBD-related CRC in The Netherlands. Age, duration of PSC and IBD, concomitant pseudopolyps, and use immunosuppressives or anti-TNF were strong prognostic factors in general hospitals.