Victoria S Kjærgaard[1,2], Camilla B Jensen[1], Johan Burisch[1], Kristine H Allin[1], Tine Jess[1]

Affiliates

[1] Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospital, The Capital Region, Copenhagen, Denmark [2] University of Glasgow, Glasgow, United Kingdom

Abstract

Background and aims:
The prognosis of paediatric onset inflammatory bowel disease (IBD) remains uncertain. An increased risk of various cancer types has been suggested, but studies are few. We aimed to determine overall and site-specific cancer risk among paediatric onset inflammatory bowel disease patients as compared to non-IBD individuals from the general population.

Methods:
We established a nationwide cohort (1977-2014) of all individuals with an IBD diagnosis before the age of 18 (n = 4,221; 2,035 with Crohn’s disease and 2,186 with ulcerative colitis) based on diagnoses from the Danish National Patient Register. For comparison, we included 42,210 randomly selected age and sex matched reference individuals from the general population. The risk of cancer was determined by using Cox proportional hazard regression and presented as hazard ratios (HR) with 95% confidence intervals (CI).

Results:
During 59,563 years of follow-up, 126 of the 4,221 paediatric onset IBD patients developed cancer (2.1 cases per 1000 person-years) as compared to 554 of the 42,210 non-IBD individuals (1.0 cases per 1000 person-years). The risk of cancer was significantly increased in IBD patients (HR 2.16; 95% CI, 1.77-2.62) with the cumulative probability after 20 years of follow-up time being 3.53% for IBD patients vs. 1.54% for non-IBD individuals. The risk was significantly higher for males (HR, 3.17; 95% CI, 2.33-4.29) than for females (HR, 1.71; 95% CI, 1.32-2.21) (p=0.003). We also observed slightly higher estimates for Crohn’s disease patients (HR 2.45; 95% CI, 1.82-3.30) than for ulcerative colitis patients (HR 1.96; 95% CI, 1.51-2.55).

Conclusion:
In this nationwide cohort study, individuals with paediatric inflammatory bowel disease had significantly increased risk of liver, small bowel, mouth, upper gastrointestinal, and colorectal cancer, but absolute numbers were still low. The impact of chronic inflammation, respectively, IBD treatments on cancer risk in early onset IBD merits further investigation.