Risk of Cancer in Paediatric onset Inflammatory Bowel Diseases: A Nation-wide Study From the epi-IIRN

Background Paediatric onset IBD [PIBD] is characterised by a more extensive phenotype than adult-onset IBD and a higher utilisation of immunosuppressive medications; both may be associated with malignancy. We aimed to assess the risk of cancer in a nationwide cohort of PIBD and to explore the risks associated with medical treatments. Methods PIBD patients [<18 years old] were included from the epi-IIRN cohort, covering 98% of the Israeli population from 2005, linked to the national cancer registry. We matched PIBD children to non-IBD children for calculating the cumulative incidence of cancer. Results In all, 3944 PIBD cases were included (2642 [67%] Crohn's disease, 1302 [33%] ulcerative colitis) translating into 23 635 person-years of follow-up, individually matched to 13 005 non-IBD children. By 30 years of age, 14 IBD patients [0.35%, 5.9/10 000 patient-years] were diagnosed with cancer and one [0.03%] with haemophagocytic-lymphohistiocytosis [HLH], compared with 14 [0.11%, 1.9/10 000 patient-years] cases of cancer {relative risk (RR) 2.5 (95% confidence interval [CI] 1.05-6.2); p = 0.04} and no HLH in the comparison-group. There were no cases of hepatosplenic T cell lymphoma, adenocarcinoma, or cholangiocarcinoma. Cancer risk was 15.6 cases/10 000 person-years in those treated with thiopurines alone (RR compared with IBD patients never exposed to either thiopurines or anti-tumuor necrosis factor [TNF] 1.8 [95% CI 0.6-6.1]; p = 0.2), 11.1/10 000 in those treated with anti-TNF alone (RR 1.3 [95% CI 0.3-6.6]; p = 0.5), and 23.1/10 000 treated with combination therapy of anti-TNF and thiopurines (RR 2.8 [95% CI 0.6-13.8]; p = 0.2). Conclusions PIBD confers an increased risk for malignancy compared with non-IBD in children. However, the absolute risk is very low and no differences in risk with specific therapies were apparent in our data.

Automated summary

Pediatric onset inflammatory bowel disease (PIBD) patients have a higher risk of developing cancer compared to non-inflammatory bowel disease (IBD) children, but the absolute risk is very low, and no significant differences in risk were found among different treatment methods in our data.