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Increased risk of small bowel cancer in IBD

Presented by
Dr J. Axelrad, New York University School of Medicine, New York, USA
ECCO 2020
In a population-based cohort of Swedish and Danish inflammatory bowel disease (IBD) patients, the risk of small bowel cancer was elevated compared with the general population, particularly among patients with Crohn’s disease (CD). However, absolute risks were still low [1].

In previous studies, CD has been associated with increased small bowel cancer risk, but these studies were limited by multiple factors resulting in exaggerated relative risks and incidence data. Data on an association between ulcerative colitis (UC) and small bowel cancer are scarce. The Swedish-Danish cohort consisted of 161,896 patients diagnosed with IBD during 1969–2017 (CD, 47,370; UC, 97,515; unclassified IBD, 17,011) and matched reference individuals from the general population.

During follow-up, 237 cases of small bowel cancer were diagnosed in the IBD group (CD, 24.4/100,000 person-years; UC, 5.88/100,000 person-years), compared with 640 cases in reference individuals (CD reference group, 2.81/100,000 person-years; UC reference group, 3.32/100,000 person-years). This corresponds to one extra case of small bowel cancer in 385 CD patients, and one extra case in 500 UC patients, followed-up for 10 years. The adjusted hazard ratio for incident small bowel cancer was 9.09 (95% CI 7.34–11.3) and 1.85 (95% CI 1.43–2.39) in CD and UC patients, respectively. Relative risks among CD patients were highest for recently diagnosed, childhood-onset, ileal, and stricturing disease; among UC patients for those with extensive colitis and primary sclerosing cholangitis. In CD patients, the risk of all small bowel cancer subtypes was increased (aHR 15.8 for adenocarcinoma, 5.51 for neuroendocrine tumours, and 4.04 for sarcoma). In UC patients, only the risk of adenocarcinoma (aHR 1.99) and neuroendocrine tumours (aHR 2.01) were increased. The authors noted that further studies should evaluate the utility of small bowel cancer surveillance in selected populations.

    1. Axelrad J, et al. ECCO-IBD 2020, OP08.

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