Incident Crohn's Disease as a Risk Factor for Colorectal Cancer in the First 10 Years after Diagnosis: A Nationwide Population-Based Study.

We investigated the risk of colorectal cancer (CRC) in patients with Crohn's disease (CD) using the claims data of the Korean National Health Insurance during 2006-2015. The data of 13,739 and 40,495 individuals with and without CD, respectively, were analyzed. Hazard ratios (HRs) were calculated using multivariate Cox proportional hazard regression tests. CRC developed in 25 patients (0.18%) and 42 patients (0.1%) of the CD and non-CD groups, respectively. The HR of CRC in the CD group was 2.07 (95% confidence interval (CI), 1.25-3.41). The HRs of CRC among men and women were 2.02 (95% CI 1.06-3.87) and 2.10 (95% CI, 0.96-4.62), respectively. The HRs of CRC in the age groups 0-19, 20-39, 40-59, and ≥60 years were 0.07, 4.86, 2.32, and 0.66, respectively. The HR of patients with late-onset CD (≥40 years) was significantly higher than that of those with early-onset CD (<40 years). CD patients were highly likely to develop CRC. Early-onset CD patients were significantly associated with an increased risk of CRC than matched individuals without CD. However, among CD patients, late-onset CD was significantly associated with an increased risk of CRC.