Prahalad said the study is both concerning and comforting at the same time.
"It's reassuring that these drugs don't seem to increase cancer risk. Clinically, these drugs really make kids better," he said. "But the study also tells us we need to be careful in monitoring children long-term to see if other studies confirm this so we can treat it early if something happens."
"For many patients with JIA, the risk-benefit analysis is very much in favor of treatment with these drugs. We use them frequently and continue to collect data looking at risk," said Dr. Brent Graham, a pediatric rheumatologist at the Monroe Carell Jr. Children's Hospital at Vanderbilt in Nashville, Tenn.
In an accompanying editorial, Drs. Karen and Kenan Onel of the University of Chicago urged caution in interpreting the study results.
The study included only a small number of children with JIA and also included children with arthritis associated with inflammatory bowel disease, a condition that may carry a higher risk of cancer.
Despite the limitations, they wrote that the research highlights the importance of long-term monitoring of children with JIA. Since the symptoms often resolve, children who no longer suffer from the condition may fall off the radar in terms of cancer risk.
"The absolute risk of late consequences of this diease and its treatment must be determined to help identify populations at special risk so that patients can continue to get the appropriate health care monitoring, even as they themselves become increasingly remote from their childhood illness," they wrote.