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Kaleb Michaud, Ph.D. |
The study is published in the current journal of Arthritis and Rheumatism by UNMC researcher Kaleb Michaud, Ph.D., and his colleague, Frederick Wolfe, M.D., of the University of Kansas School of Medicine.
The researchers set out to assess the risk of various cancers associated with anti-TNF treatments — also called biologics — which are administered through injection or infusion. Dr. Wolfe and Dr. Michaud also analyzed tumor necrosis factor alpha (TNFα) blocker drugs — etanercept, infliximab and adalimumab.
The researchers studied the incidence of cancer in 13,001 RA patients from 1998 to 2005. Nearly half of patients, 49 percent, had a history of exposure to anti-TNFα drugs.
Researchers found 623 cases of skin cancer and 537 cases of other cancers.
Their conclusions support previous epidemiologic study findings that patients using anti-TNF treatments have an increased risk of melanoma and certain skin cancers. However, contrary to previous national study findings, researchers did not find an increased risk of lymphoma related to treatment with TNFα blockers.
The new information may offer reassurance to patients with RA being treated with etanercept or infliximab, the researchers said.
“The study is the largest of its kind in the United States and it adds a lot of evidence showing these TNFs aren’t as bad as the initial clinical trials showed them to be,” said Dr. Michaud, assistant professor of medicine, rheumatology and immunology section, UNMC Department of Internal Medicine. “Physicians were very concerned if someone with RA developed cancer because of the fear that these medications might cause cancer. But we’re not finding this association.”
Dr. Michaud said there’s been a longtime association between RA and cancer, but it’s not clear what the relationship is.
“We found an increase with skin cancers and in lymphoma with RA, which has been shown in the past,” he said. “We also show a decrease in breast cancer and colon cancer, which has been shown by other very large cohorts. However, we don’t show any associations with any other cancers with these drugs that other people have reported.”
For their data, Drs. Wolfe and Michaud turned to two sweeping databases, the National Data Bank for Rheumatic Diseases and the U.S. National Cancer Institute Surveillance, Epidemiology and End-Results.
“There was an important study last year that suggested that taking biologics increased the risk for lymphoma by a lot,” Dr. Michaud said. “But our study doesn’t have that association.”
Whether the 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 TNFα blockers.
“Although our data do not show associations between malignancy and biologic therapy, except for skin cancers, our subjects’ mean and median exposure to biologics was only three years,” Dr. Michaud said. “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 three-year time frame.”
RA is a chronic disease that causes pain, stiffness, swelling, and limitation in the motion and function of multiple joints. Though joints are the principal body parts affected by RA, inflammation can develop in other organs as well.