The relationship between rheumatoid arthritis (RA), an autoimmune disease marked by chronic inflammation of the joints and tissue surrounding vital organs, and the incidence of cancer is complicated.
Epidemiologic studies have generally demonstrated that blood, lung, and skin cancers are increased among RA patients, while breast and colon cancers are decreased. Whether these cancer rates are caused by the nature of RA or by immunosuppressive drugs used to treat RA is an issue of ongoing debate and investigation. Findings of various clinical trials and observational studies conflict over the risk of malignancy related to the use of tumor necrosis factor alpha (TNFá) blockers, a biologic therapy shown effective at controlling the symptoms of RA in patients who fail to respond to traditional disease-modifying antirheumatic drugs (DMARDs).
To assess the risk of cancer among biologic-treated RA patients, comprehensively and conclusively, two research specialists, Frederick Wolfe, MD, University of Kansas School of Medicine, and Kaleb Michaud, PhD, University of Nebraska Medical Center, turned to two sweeping databases, the National Data Bank for Rheumatic Diseases and the US National Cancer Institute SEER (Surveillance, Epidemiology, and End-Results). Gathering and comparing data from both, they studied the incidence of cancer in 13,001 RA patients, over a total span of close to 49,000 years. Nearly half of these patients, 49 percent, had a history of exposure to anti-TNFá drugs. As Dr. Wolfe and Dr. Kaleb found, and report in the September 2007 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis), biologic treatment of RA increases a patient's risk of skin cancers, including melanoma, but not any other specific cancers—not lung, liver, brain, or bone cancers, not Hodgkin's or leukemia, not solid tumors or lymphoma—and not of developing cancer in general.