OP22 The risk of cancer in pediatric-onset immune-mediated inflammatory diseases – a nationwide Danish study from 1980-2018

Abstract Background A higher risk of cancer has been reported among patients with adult-onset immune-mediated inflammatory disease (IMID). However, data on in paediatric-onset IMIDs (pIMID) are scarce. In this nationwide study from 1980 to 2018, we investigated the Danish pIMID population compared controls background population. Methods PIMID was defined as registered National Patient Registries one or more following diagnoses: bowel (pIBD), rheumatic (pRD), autoimmune idiopathic liver (pAILD) before their 18th birthday. Each case matched up 10 Cancer diagnoses were verified using Registry. Risk calculated Cox proportional regression analysis and presented hazard ratios (HR) 95% confidence intervals (95% CI). Results We identified 13 216 cases, consisting 5 811 pIBD (44%), 7 241 pRD (55%) 347 pAILD (2%), 114 502 controls. Median age at diagnosis 12.5 years. Follow-up time 11.1 10.5 years for cases controls, respectively. The overall HR 2.1 (95%CI: 1.8-2.4), p<0.001. 2.4 2.0-3.0), p<0.001 pIBD, ascribed colorectal-, liver-, skin lymphoma, 1.6 1.2-2.1), p=0.002 pRD, lymphoproliferative cancer, 5.7 2.5-13.1), pAILD, cancer. Patients multiple IMID had an increased only (HR 2.8 [95%CI: 1.9-4.1], p<0.001). Conclusion associated a twofold colorectal pRD.