Patients with rheumatoid arthritis (RA), an autoimmune, inflammatory disease marked by progressive joint and organ damage, face a high risk of developing cancer. Their vulnerability, especially to lymphoma and leukemia, may be due to the nature of RA. Disease-modifying antirheumatic drugs (DMARDs) including tumor necrosis factor alpha (TNF) antagonists, a type of biologic DMARD have also been implicated. TNF blockers, which work by attaching to and impeding chemical messengers behind inflammation, have had a significant impact on the treatment of RA. They have also been linked to lymphoma among users. In fact, reports of lymphoma prompted the Food and Drug Administration to mandate adding a cancer risk warning to the labels of three TNF blockers: etanercept (Enbrel), infliximab (Remicade), and adalimumab (Humira).
Motivated by persistent concerns and inconclusive studies, researchers at Harvard Medical School's Brigham and Women's Hospital set out to investigate the association between treatment with TNF blockers and occurrence of cancer in a large sample of patients with RA. Their results, featured in the September 2006 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis), indicate that biologic DMARD therapy poses no greater risk for cancer than therapy with a standard prescription DMARD, methotrexate (MTX).
The researchers focused on 7,830 RA patients, age 65 and older, drawn from healthcare databases in New Jersey, Pennsylvania, and British Columbia, Canada. Subjects included 1,152 biologic DMARD users and 7,306 MTX users. Of those treated with a biologic DMARD, 64 percent had used etanercept, 33 percent had used infliximab, and the remaining 2 percent had used anakinra (Kineret). 55 percent had previously used MTX and 39 percent were receiving MTX when they began anti-TFN therapy.