Risk Factors

The risk of developing colorectal cancer is increased in people with IBD, and is higher the more of the colon that is involved. Recent studies estimate that, although the occurrence of colon cancer in people with ulcerative colitis has decreased over the last 60 years to 1.2 in 1000 patients in any year, the risk increases the longer someone has IBD.^1,4

It takes 8–10 years after Crohn’s disease or ulcerative colitis develops for the risk of CRC to become noticeable.^1,2,5

Risk factors for colorectal cancer include: extensive colitis, young age at diagnosis, family history of CRC and persistent inflammation of the colon.⁶

In the persistent inflammation state, the chronically inflamed and ulcerated lining of the colon is constantly re-growing and re-healing, and so is more prone to cancer-causing mutations, putting the entire colon lining at risk for producing precancerous cells.^7,8

References:
1: Van Assche G, Dignass A, Bokemeyer B, et al. Second European evidence-based consensus on the diagnosis and management of ulcerative colitis part 3: special situations. J Crohns Colitis 2013; 7: 1–33.
2: Rubin DC, Shaker A, Levin MS. Chronic intestinal inflammation: inflammatory bowel disease and colitis-associated colon cancer. Front Immunol 2012; 3: 107.
4: Castaño-Milla C, Chaparro M, Gisbert JP. Systematic review with meta-analysis: the declining risk of colorectal cancer in ulcerative colitis. Aliment Pharmacol Ther 2014; 39: 645–59.
5: Eaden JA, Abrams KR, Mayberry JF. The risk of colorectal cancer in ulcerative colitis: a meta-analysis. Gut 2001; 48: 526–35.
6: Sebastian S, Hernández V, Myrelid P, et al. Colorectal cancer in inflammatory bowel disease: results of the 3rd ECCO pathogenesis scientific workshop (I). J Crohns Colitis 2014; 8: 5–18.
7: Triantafillidis JK, Nasioulas G, Kosmidis PA. Colorectal Cancer and Inflammatory Bowel Disease: Epidemiology, Risk Factors, Mechanisms of Carcinogenesis and Prevention Strategies. Anticancer Res 2009; 29: 2727–37.
8: Velayos FS, Loftus EV, Jess T, et al. Predictive and protective factors associated with colorectal cancer in ulcerative colitis: A case-control study. Gastroenterology 2006; 130: 1941–9.