OP08 Inflammatory bowel disease and risk of small bowel cancer: A binational population-based cohort study from Denmark and Sweden

Abstract

Abstract Background Crohn’s disease (CD) is associated with increased risk of small bowel cancer (SBC), but previous studies were limited by a small number of cases, short follow-up, lack of individually matched comparators, and over-representation of tertiary referral centres, leading to exaggerated relative risks and incidence data. Data on ulcerative colitis (UC) and SBC are scarce. Methods In a binational, population-based cohort study from Sweden and Denmark of patients diagnosed with inflammatory bowel disease (IBD) during 1969–2017 and matched reference individuals from the general population, we evaluated the risk of incident SBC, including SBC subtypes (small bowel adenocarcinoma, neuroendocrine tumours, and sarcoma). Cox regression was used to compute adjusted hazard ratios (aHRs) as a measure of relative risks for incident SBC and SBC subtypes. Results We identified 161,896 individuals with IBD (CD: 47,370; UC: 97,515; unclassified IBD:17,011). During follow-up, 237 cases of SBC were diagnosed in patients with IBD (CD: 24.4/100,000 person-years; UC: 5.88/100,000 person-years), compared with 640 cases in reference individuals (2.81/100,000 person-years and 3.32/100,000 person-years, respectively, Table). This corresponded to one extra case of for small bowel cancer in 385 CD patients, and one extra case in 500 UC patients, followed-up for 10 years. The aHR for incident SBC of 9.09 (95% CI = 7.34–11.3) in CD patients and 1.85 (95% CI = 1.43–2.39) in UC patients (Figure). When the first year after IBD diagnosis was excluded, the aHRs for incident SBC decreased to 4.96 in CD patients and 1.69 in UC patients. Among CD patients, relative risks were highest for recently diagnosed, childhood-onset, ileal, and stricturing CD; among UC patients, relative risks were highest for those with extensive colitis and primary sclerosing cholangitis (PSC). In CD patients, the risk of all SBC subtypes was increased (aHR 15.8 for adenocarcinoma, 5.51 for neuroendocrine tumours, and 4.04 for sarcoma) whereas in UC patients only the risk of adenocarcinoma (aHR 1.99) and neuroendocrine tumours (aHR 2.01) were increased. Conclusion SBC was more common in IBD patients, particularly among patients with CD, although absolute risks were low. Further studies should evaluate the utility of SBC surveillance in selected populations such as those with ileal CD, extensive colitis, or UC-PSC.