Children and adolescents with immune-mediated inflammatory disease carry a 2-fold higher risk for cancer.

A Danish case-control study investigated the risk for malignomas in pediatric patients with immune-mediated inflammatory disease (pIMID). The pIMID diagnoses included IBD, autoimmune idiopathic liver disease (AILD), and rheumatic disease. As per definition, patients had to be under 18 and have two diagnostic codes for pIMID between 1980 and 2018, or one entry plus one disease-related treatment. Each case was matched with up to 10 controls from the general population.

The study cohort consisted of 13,216 patients with pIMID (IBD, 5,811; AILD, 329; rheumatic disease, 7,241) and 114,502 controls. The median age at pIMID diagnosis ranged from 9.9 to 14.9 and the median follow-up ranged from 9.0 to 11.6 years.

A total of 207 cases of cancer were identified among patients with pIMID and 847 among the controls. “We found a two-fold increased risk of cancer in patients with pIMID compared with the background population,” Andrea Ehrström, of Hvidovre Hospital in Denmark, noted. She also commented on the HR of 2.1 (P<0.0001) that was determined by Cox regression. This significantly increased risk varied depending on the type of pIMID: for IBD, the HR 2.4; it was 5.7 for AILD and 1.6 for rheumatic disease. After stratification according to cancer site, pediatric patients with IBD and AILD had a significantly increased risk for colorectal cancer, liver cancer, and non-melanoma skin cancer. Furthermore, there was an approximately 2-fold risk for melanoma in IBD together with a nearly 5-fold risk for lymphoma (HR, 4.8). For rheumatic disease, the augmented hazard of cancer was significant for lymphoma (HR, 2.7) and leukemia (HR, 5.7). The investigation also looked at the possible influence of more than one pIMID diagnosis on the overall cancer risk and established an HR of 2.8 compared with only one pIMID.

“The increased risk for cancer corresponds to 1.2 cancer cases per 1,000 patient-years among patients with pIMID compared with 0.6 cancer cases per 1,000 patient-years among the controls,” Ehrström added.

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