Editorial: Mortality in immune-mediated inflammatory diseases during early adulthood—Authors' reply

We are grateful to Dr. Henderson for the kind words in his editorial1 and for accurately summarising our paper.2 As Dr. Henderson recognised, cancer was a leading cause of mortality in our nationwide cohort of patients diagnosed with paediatric-onset immune-mediated inflammatory disease (pIMID). This suggests that IMID affects the risk of cancer, which is well known in paediatric-onset inflammatory bowel disease (pIBD), where young age at diagnosis seems to be a risk factor.3-5 Much less is known about the risk of cancer in paediatric-onset autoimmune liver disease (except for cholangiocarcinoma6), and for rheumatic diseases, the literature is contradictory.7, 8 It is generally believed that the inflammatory changes in IBD increase the risk of adenocarcinomas, while thiopurines and maybe tumour necrosis factor-alpha (TNF-α) antagonists increase the risk of lymphomas and skin cancers.9 If true, other IMIDs would be expected to increase the risk of cancers in the affected organs and, if treated with thiopurines or anti-TNF-α agents, also increase the risk of lymphoma and skin cancers. We tested this hypothesis using the same source population as the present study (unpublished data). We found increased cancer risks across all included pIMIDs and that site-specific cancer risks depended on the type of IMID. Lastly, we found that thiopurines were associated with lymphoma and skin cancer, while anti-TNF-α agents and calcineurin inhibitors were associated with lymphomas.