(HealthDay News) – Children with juvenile idiopathic arthritis (JIA) are significantly more likely to develop cancer than children without the condition, although common treatments have no effect on risk, according to a study published online Feb. 10 in Arthritis & Rheumatism.

Timothy Beukelman, MD, from the University of Alabama at Birmingham, and colleagues compared relative rates of incident malignancy in 7,812 children with JIA, 652,234 children with asthma, and 321,821 children with attention-deficit/hyperactivity disorder (ADHD). Children with JIA were categorized according to treatment with methotrexate and tumor necrosis factor (TNF) inhibitors, as ever or never exposed. Incident malignancies were classified as possible, probable, or highly probable. Standardized incidence ratios (SIRs) were assessed using the 321,821 children with ADHD as a reference group.

The researchers found that, for probable and highly-probable malignancies, the SIR for children with JIA was 4.4 (95% CI, 1.8–9). The SIR was 3.9 (95% CI, 0.4–14) for methotrexate users without TNF inhibitor use, and the SIR was zero (95% CI, 0–9.7) following the use of any TNF inhibitors.

“Children with JIA appeared to have an increased rate of incident malignancy compared to children without JIA,” Beukelman and colleagues conclude. “JIA treatment, including TNF inhibitors, did not appear significantly associated with the development of malignancy.”

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