Cancer rate 4 times higher in children with juvenile arthritis

New research reports that incident malignancy among children with juvenile idiopathic arthritis (JIA) is four times higher than in those without the disease. Findings now available in Arthritis & Rheumatism, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology (ACR), suggest JIA treatment, such as tumor necrosis factor (TNF) inhibitors, does not necessarily explain the development of cancer in this pediatric population.

Children with JIA experience symptoms similar to adults with arthritis including joint pain, swelling, tenderness and stiffness. JIA is a general term used to describe the various chronic arthritis diseases in children and affects roughly 294,000 under the age of 17 in the U.S. according to a 2008 report from the National Arthritis Data Workgroup.

One of the drug types used to treat childhood and adult arthritis, along with a number of other rheumatic conditions, is TNF inhibitors. Studies have reported that more than 600,000 people worldwide have received anti-TNF therapy since their introduction 15 years ago. However, possible cancer risk has been associated with treatment, prompting the U.S. Food and Drug Administration (FDA) to place "black box" warnings of the potential malignancy risk on TNF inhibitors labels.

In the present study Dr. Timothy Beukelman from the University of Alabama at Birmingham and colleagues conducted one of the largest investigations into the rates of incident malignancy among JIA pediatric patients relative to their treatment. Using data from the U.S. Medicaid records from 2000 through 2005, researchers identified 7,812 children with JIA and two comparator groups without JIA; one group with asthma (652,234 children) and the second with attention-deficit hyperactivity disorder (ADHD; 321,821 children).

The team categorized patients' treatment with methotrexate and TNF inhibitors as "ever" or "never" used, though many children with JIA did not receive either of these treatments during the study. The research team did not have access to detailed medical records, and therefore categorized the identified incident malignancies as "possible," "probable," or "highly probable."

Although cancer is a leading cause of death among children in the United States, childhood cancer deaths are declining.

In the United States, cancer is the second most common cause of death among children between the ages of 1 and 14 years, surpassed only by accidents. More than 16 out of every 100,000 children and teens in the U.S. were diagnosed with cancer, and nearly 3 of every 100,000 died from the disease. The most common cancers in children were leukemia (cancer of the bone marrow and blood) and brain and central nervous system cancers.

Leukemias

In 2005,* 4.1 of every 100,000 young people under 20 years of age in the U.S. were diagnosed with leukemia, and 0.8 per 100,000 died from it. The number of new cases was highest among the 1–4 age group, but the number of deaths was highest among the 10–14 age group.