Mikkel Malham[1], Christian Jakobsen[1,2], Anders Paerregaard[1], Lauri Virta[3], Kaija-Leena Kolho[4,5], Vibeke Wewer[1]

Affiliates

1: The Paediatric Department, Copenhagen University Hospital, Hvidovre, Denmark. 2: The Gastro Unit, Medical Division, Copenhagen University Hospital, Hvidovre, Denmark. 3: The Research Department, the Social Insurance Institution, Turku, Finland. 4: The Paediatric Department, Tampere University Hospital and Tampere University, Tampere, Finland. 5: Faculty of Medicine, University of Helsinki, Helsinki, Finland

Abstract

Background:
Recent studies report increased risks of both cancer and mortality in paediatric onset inflammatory bowel disease (pIBD) but the reproducibility of this is unknown. In this population-based study we aim to estimate the incidence of cancer and mortality in the Danish and Finnish pIBD population in a 23-year period.

Methods:
The pIBD population was defined as individuals registered in the national patient registries with a diagnosis of Crohn’s disease, ulcerative colitis or IBD-unclassified before their 18th birthday from 1992 to 2014. This cohort was cross referenced with the national cancer and mortality registries identifying all pIBD patients who subsequently developed cancer and / or died and followed up to the end of 2014. Risk estimates are presented as standardized incidence ratios calculated based on incidence figures from the populations.

Results:
6,689 patients with pIBD were identified. Of these, 72 subsequently developed cancer and 65 died. The standardized incidence ratio of cancer in general was 2.5 (95% confidence interval (CI): 2.0-3.2). The cancer specific standardized incidence ratios were: colorectal cancer: 15.3 (CI: 8.7-24.8), liver cancer: 42.8 (CI: 19.5-81.3), skin cancer: 4.2 (CI: 2.4-6.7), and lymphomas: 2.9 (CI:1.4-5.3). The standardized mortality ratio was 3.0 (CI: 2.4-3.9) with the main causes of mortality being cancer, infections and suicides (standardized mortality ratio 3.8 [CI: 2.2-6.0]).

Conclusion:
We found an increased risk of cancer and mortality in pIBD. These findings are in line with recently pub-lished data. However, we found a surprisingly high frequency of suicides in the pIBD population. The pre-sent study underlines not only the importance of cancer surveillance programs being implemented in the standard of care in adolescent pIBD patients but also the importance of a holistic, multi-disciplinary patient care in both the paediatric and the adult care setting.