Melanoma, Rheumatoid Arthritis and Methotrexate
Rheumatoid Arthritis (RA) patients who are also using the drug methotrexate may also be facing an increased risk of lymphoma, leukemia, myeloma and lung cancer. Researchers in Australia, where over 2 percent of the adults have RA, studied cancer incidence in RA patients who also used methotrexate (MTX) . An article in the June issue of Arthritis Care & Research reports that their findings suggest an increased risk of malignancies in patients treated with MTX.
The study focused on 459 RA patients, 309 women and 150 men, regularly seen by 1 of 6 rheumatologists based in Melbourne. All had started treatment with MTX prior to June 1986. The majority had no previous history of immunosuppressant therapy. 61 percent were rheumatoid factor positive.
Those RA patients also on MTX were found to have an estimated 50 percent excess risk of developing cancer in any form. Risk of non-Hodgkin's lymphoma was greater than 5 times the risk in the general population. They also have 3 times the risk of melanoma and lung cancer.
The study's major limitation is that there was no control group of RA patients who were not using methotrexate. However, Dr. Rachelle Buchbinder, the study's lead author, feels that the study will have important implications in regard to the risk of melanoma in rheumatoid arthritis patients.
"Further investigation is needed to determine whether this risk is unique to Australia and what role MTX, immunosuppression per se, and/or environmental factors such as exposure to UV radiation play in its development," Dr. Buchbinder stresses. "Our findings, taken together with other studies investigating the risk of skin cancer in patients with RA, may support a role for regular skin cancer screening for all patients with RA, particularly those receiving immunosuppressive therapy."
