Cancer Risks in IBD: Beyond Colorectal Cancer

Risks for intestinal and extraintestinal cancers in inflammatory bowel disease (IBD) have mostly been estimated in studies from specialized centers. More population-based studies are needed to estimate these risks among the general population with IBD.

In the current population-based study, investigators prospectively assessed various cancer risks in a cohort of 1437 patients with ulcerative colitis (UC) and 774 patients with Crohn disease (CD). Study participants were diagnosed with IBD from 1978 to 2002 in one of seven local hospitals in a region of Denmark.

Median follow-up was 15 years in patients with UC and 14 years in patients with CD. Overall cancer risk was elevated in patients with CD (standardized incidence ratio, 1.55) but not in those with UC. The risk for colorectal cancer was elevated in men with CD (SIR, 2.43; 95% confidence interval, 1.05–4.78) and tended toward elevation in CD patients overall and in smokers. Risk for colorectal cancer was not elevated in patients with UC. Two cases of small-bowel cancer occurred in the total cohort compared with 0.13 cases expected (SIR, 15.18; 95% CI, 1.84–54.78). With regard to extraintestinal cancers, patients with UC were at excess risk for prostate cancer (SIR, 1.82), and patients with CD were at excess risk for lung cancer (SIR, 2.13; particularly females [SIR, 3.40] and smokers [SIR, 3.02]), cervical dysplasia (SIR, 1.65; particularly those diagnosed at ages 0–19 [SIR, 2.52], smokers [2.15], and thiopurine users [SIR, 2.47]), and lymphoma (SIR, 3.01; particularly non-Hodgkin lymphoma [SIR, 3.43]). Thiopurine use was not associated with increased risk for lymphoma.