Risk factors for colorectal neoplasia in patients with underlying inflammatory bowel disease: a multicenter study.

Background: This study sought to evaluate the risk factors for the development of colitis-associated neoplasia (CAN) in Chinese patients with inflammatory bowel disease (IBD). Methods: IBD patients who developed CAN between 1999 and 2016 were identified from eight medical centers. In addition to initial pathology evaluation, a CAN diagnosis was confirmed by two expert pathologists. Patients with CAN (n=29) were compared with non-CAN controls (n=87). Matching was performed for gender and IBD type with a ratio of three controls to one subject. Results: Of the 29 patients with CAN, 8 (27.6%) had colorectal cancer (CRC), 20 (69.0%) had a final diagnosis of low-grade dysplasia and 1 (3.4%) had high-grade dysplasia. Multivariate analysis revealed that an older age at the time of IBD diagnosis and a longer IBD duration were independent risk factors for the development of CAN, with odds ratios of 1.09 [95% confidence interval (CI): 1.04-1.14, P<0.001] and 1.14 (95% CI: 1.03-1.27, P=0.013), respectively. Comparison between IBD patients with CRC and those with dysplasia indicated that the former were older at the time of IBD diagnosis (P=0.012) and had longer IBD durations (P=0.019). Conclusions: Older age at the time of IBD diagnosis and longer IBD duration were found to be associated with the development of CAN in IBD patients.