Epidemiology and Risk Factors for Colorectal Cancer in Inflammatory Bowel Diseases

Abstract

Colorectal cancer (CRC) is a dreaded complication of inflammatory bowel disease (IBD), accounting for up to 15% of IBD-related deaths. Chronic or recurrent mucosal inflammation leads to widespread genetic mutations within colitic mucosa, increasing CRC risk in IBD patients. Pooled risk estimates for CRC risk among IBD patients range between 1.5- and 2-fold higher than background risk across meta-analyses of population-based studies and 4- and 6-fold higher than background risk in meta-analyses of referral center studies. Paralleling CRC risk, the mortality risk from CRC in IBD patients has ranged between 1.2- and 2-fold higher than background across population-based studies. European studies have reported declining CRC risk over time, whereas North American studies have reported stable CRC risk among IBD patients, compared with persons in the general population. Risk factors for CRC in IBD patients include increasing age, longer duration of disease, greater extent of colitis, greater disease severity, and the presence of primary sclerosing cholangitis. IBD-associated CRC affects patients at a younger age than sporadic CRC, leading to a higher relative risk of CRC among younger patients with IBD as compared with younger persons without IBD.