A rule for determining risk of colorectal cancer in patients with inflammatory bowel disease

Surveillance guidelines for inflammatory bowel disease-associated colorectal cancer (IBD-CRC) are based on findings from retrospective studies. We aimed to create and validate a prediction rule to assist clinicians in identifying patients with IBD who are at low and high risk for CRC.

We performed a retrospective case-control study of 2 cohorts of patients from tertiary care centers (the University Hospital of Leuven, Belgium, and 7 University Medical Centers in The Netherlands). Multivariate Cox regression was used to select independent risk factors for CRC in the Leuven cohort. Based on their regression coefficients (β), we created a rule to predict risk for CRC. In validation studies, the predictive strength was tested by C-statistic analysis and then validated externally in the Dutch cohort.

In total, we identified 50 patients with IBD-CRC (cases) and 136 patients with IBD without CRC (controls) in Leuven, and 138 cases and 206 controls in the Dutch cohort. From the Leuven cohort we created the CRC risk prediction rule based on 4 risk factors: IBD-type ulcerative colitis (β = 1.2), primary sclerosing cholangitis (β = 1.1), extent of colonic disease ≥50% (β = 1.1), and postinflammatory polyps (β = 0.8). The prediction rule consisted of a total score for each individual patient calculated from the presence or absence of these 4 risk factors. For example, a score of 13 represented patients who had extensive Crohn's disease without PSC or postinflammatory polyps, who had a 15% likelihood of CRC in the Leuven cohort and a 24% likelihood of CRC in the Dutch cohort. Scores of 0, 13, 23, 27, and 37 represented patients with Crohn's disease, and scores 15, 25, 28, 38, 42, and 52 represented patients with ulcerative colitis. The total score per patient had a C-statistic of 0.75. In the Dutch cohort this score had a C-statistic of 0.67.

Ulcerative colitis, primary sclerosing cholangitis, disease extent ≥50%, and postinflammatory polyps were found to determine risk for CRC in patients with IBD. A surveillance guideline that incorporates the relative weights of these risk profiles would identify patients at risk for CRC more accurately than algorithms in current guidelines.