Has the risk of colorectal cancer in inflammatory bowel disease decreased?

Abstract

The association between inflammatory bowel disease (IBD) and colorectal cancer (CRC) has been acknowledged for almost a century and is assumedly promoted by a chronic inflammation-driven carcinogenic process in the intestine in combination with a genetic predisposition. The magnitude of the risk of CRC in IBD remains a continuing subject of debate. The early, high risk estimates for CRC in IBD were most likely overestimated due to selected patient populations originating from tertiary referral centers with a disproportional high percentage of patients with severe disease. Later population-based studies calculating risk estimates from a broad spectrum of IBD patients have found the risk to be significantly lower. At present, there is evidence that IBD patients with longstanding and extensive disease with uncontrolled inflammation are those at increased risk. Additional, other recognized risk factors include early age at onset, family history of CRC, and concomitant primary sclerosing cholangitis. A significant amount of effort is put into identifying potential preventive factors of CRC in IBD, including surveillance programs and chemopreventive agents but the individual effect of these remains uncertain. Interestingly, recent studies have reported a decline in risk of CRC over time. Surveillance programs and the new treatment strategies, particular biological treatment might be part of the reason for the observed decline in risk of CRC in IBD over time but future studies will have investigate this assumption.

Keywords: Inflammatory bowel disease, Colorectal cancer, Risk, Ulcerative colitis, Crohn’s disease

Core tip: The increased risk of colorectal cancer in inflammatory bowel disease is well established. But what is the true magnitude of this increased risk, does the risk of colorectal cancer differ between ulcerative colitis and Crohn’s disease and what are the significant risk factors? Further, recent studies have indicated that the risk of colorectal cancer in patients with inflammatory bowel disease is decreasing over time, potentially due to improved treatment options that lower the inflammatory burden. These are some of the subjects that will be elucidated and discussed in this review.