P778 Risk of cancer in paediatric onset inflammatory bowel disease: a nationwide cohort study 1977–2014

Abstract

Background: The prognosis of paediatric onset inflammatory bowel disease (IBD) remains uncertain. We examined the overall and site‐specific cancer risk among paediatric onset IBD patients when compared with non‐IBD individuals from the general population. Methods: Based on the Danish National Patient Register, we established a nationwide cohort (1977‐2014) of all individuals recorded with IBD before the age of 18 (n = 4,221) and 42,210 randomly selected age‐and sex‐matched individuals from the general population. The risk of cancer was determined using Cox proportional hazard regression. Results: During 59,563 person‐years of follow‐up, 126 of 4,221 paediatric onset IBD patients developed cancer (2.1 cases per 1000 person‐years) when compared with 554 of 42,210 non‐IBD individuals (1.0 case per 1000 person‐years). Accordingly, the hazard ratio (HR) of any cancer was 2.16 (95% CI, 1.77‐2.62) with a slightly higher risk in Crohn's disease (HR, 2.45; 95% CI, 1.82‐3.30) than in ulcerative colitis (HR, 1.96; 95% CI, 1.51‐2.55). Males with paediatric onset IBD (HR, 3.17; 95% CI, 2.33‐4.29) had a significantly higher risk of cancer than females (HR, 1.71; 95% CI, 1.32‐2.21). When examining site‐specific cancers, the risk of liver, upper gastrointestinal, small bowel and colorectal cancer was significantly increased. Conclusions: This nationwide cohort study showed a significantly increased relative risk of cancer in paediatric onset IBD. The risk was highest for liver, upper gastrointestinal, small bowel and colorectal cancer and was not influenced by medical treatment. Still, absolute numbers were low with only 1 additional cancer case per 1000 person‐years of follow‐up. This is important information to patients and clinicians.