No significant link found between treatments used for juvenile idiopathic arthritis and development of cancer
Research Activities, August 2012, No. 384
Juvenile idiopathic arthritis (JIA) is an autoimmune disease that usually occurs in children before age 16. It can cause joint pain and swelling, fevers, and rash. Treatment includes therapy with methotrexate (MTX) and tumor necrosis factor (TNF) inhibitors. The latter class of drugs, which inhibit the ability of TNF, an inflammation-producing protein that also can kill cancer cells, has been associated with a risk of malignancy. A new study has found a higher rate of incident malignancy in children with JIA compared to children with attention deficit hyperactivity disorder (ADHD) or asthma. However, the type of treatment for JIA was not significantly associated with a child developing a malignancy.
Researchers used Medicaid claims data obtained from all 50 States and the District of Columbia. Children diagnosed with JIA were identified. Children without JIA who had asthma (652,234) or ADHD (321,821), chronic disorders that are not suspected to be associated with cancer, were used for comparison. The researchers also categorized the children with JIA by their exposure to MTX and TNF inhibitors. Using diagnostic codes, procedure codes, and pharmacy claims, they identified incident malignancies that developed in the children.
Nearly half of the 7,812 children with JIA had taken MTX; one-fifth had taken TNF inhibitors. There were a total of 265 malignancies found: 10 in the JIA group, 68 in the ADHD group, and 193 in the asthma group. Six of the 10 malignancies in the JIA group were identified in children who had not taken MTX, TNF inhibitors, or other immune-system agents. Three malignancies were found in JIA patients taking only MTX; 1 malignancy was found in a child taking a TNF inhibitor for JIA. The standardized incidence ratio was 4.4 for malignancies in the children with JIA compared to children without the disease. No significant association was found between cancer and treatment of JIA with either MTX or TNF inhibitors. The study was supported in part by the Agency for Healthcare Research and Quality (HS17919 and HS18517).
See "Rates of malignancy associated with juvenile idiopathic arthritis and its treatment," by Timothy Beukelman, M.D., M.S.C.E., Kevin Haynes, Pharm.D., Jeffrey R. Curtis, M.D., M.S., M.P.H., and others in the April 2012 Arthritis & Rheumatism 64(4), pp. 1263-1271.