(ChemotherapyAdvisor) – Children with juvenile idiopathic arthritis (JIA) have an increased rate of incident malignancy compared to children without JIA, which does not appear to be linked to treatment with TNF inhibitors, a study published in Arthritis & Rheumatism online February 10 has found.

The authors used U.S. Medicaid physician diagnosis codes and dispensed-medication prescription data from 2000–2005 to identify cohorts of 7,812 children with JIA and 321,821 children without JIA. Those with JIA represented 12,614 person-years of follow-up, and 1,484 children contributed 2,922 person-years of TNF inhibitor exposure.

For children with (vs. without) JIA, standardized incidence ratio was 4.4 (1.8–9.0) for probable and highly probable malignancies; for methotrexate users without TNF inhibitor use, SIR was 3.9 (0.4–14). No probable or highly probable malignancies were identified (SIR 0 (0–9.7)) following any use of TNF inhibitors.

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The authors noted that in 2009, the FDA issued a warning about the possible association between TNF inhibitors and cancer risk in children; however, the analyses did not account for methotrexate exposure “or possible carcinogenic effects of the JIA disease process itself.” These data suggest risk from use of anti-TNF agents for JIA may be smaller than initially believed.