Study finds increased skin cancer risk associated with biologic treatment of RA patients

Only skin cancer was associated with use of anti-TNFá therapy; no association was found for other tumors or lymphoma.

Treating rheumatoid arthritis patients using biologic therapies, such as tumor necrosis factor alpha blockers, increases their risk of developing skin cancers, including melanoma, but not any other specific cancers, according to a study.

Epidemiologic studies have generally demonstrated an increased rate of blood, lung and skin cancers among rheumatoid arthritis (RA) patients and a decreased rate of breast and colon cancers. However, uncertainty remains regarding whether these cancer rates are caused by the nature of RA or by immunosuppressive drug treatment. Also, various clinical trials and observational studies have found conflicting evidence regarding the risk of malignancy related tumor necrosis factor alpha (TNFá) blockers.

Frederick Wolfe, MD, of the University of Kansas School of Medicine, and Kaleb Michaud, PhD, of the University of Nebraska Medical Center, investigated the risk of cancer among biologic-treated RA patients. The researchers reviewed data collected in the National Data Bank for Rheumatic Diseases and in the U.S. National Cancer Institute Surveillance, Epidemiology and End-Results (SEER) database.

The study examined the incidence of cancer in 13,001 RA patients over roughly 49,000 patient-years. Nearly half of these patients — 49% — had a history of exposure to anti-TNFá drugs, according to the study, published in Arthritis & Rheumatism.

The researchers identified 623 cases of skin cancer and 537 cases of other cancers.

After controlling for variables, including gender, smoking history, education level, disease severity and baseline prednisone use, anti-TNFá therapy was linked to an increased risk of skin cancers only, with a 2.3 odds ratio for developing melanoma.

Biologic use had no impact on any other type of cancer; the overall risk for all malignancies was 1.0. This finding was substantially different from the overall risk of 3.3 noted in a meta-analysis of clinical trials of biologic RA treatments, according to a press release announcing the study results.

"Although our data do not show associations between malignancy and biologic therapy, except for skin cancers, the mean and median exposure to biologics was only 3 years," Michaud said in the release.

"It is possible that with increasing time of follow-up or of exposure, the association between malignancy and biologic therapy would become stronger. However, true associations are regularly seen within this time frame," he said.

For more information:
Wolfe F, Michaud K. Biologic treatment of rheumatoid arthritis and the risk of malignancy: Analyses from a large U.S. observational study. Arthritis Rheum. 2007;56:2886-2895.