Rheumatoid Arthritis Drug Methotrexate Raises Cancer Risk

What Studies Have Revealed

Methotrexate has been tied to an increased risk of melanoma, as well as other malignancies, for rheumatoid arthritis patients treated with the medication. An Australian study compared 459 rheumatoid arthritis patients (309 women and 150 men who started taking methotrexate before June 1986) to the general population to determine cancer risk.

According to study results, published in the June 2008 Arthritis Care and Research, rheumatoid arthritis patients who were treated with methotrexate were found to have a 50% increased risk of developing any form of cancer.

The risk of non-Hodgkins lymphoma was more than 5 times greater in rheumatoid arthritis patients than in the general population. Rheumatoid arthritis patients also were found to have triple the risk of lung cancer and triple the risk of melanoma.

The findings for non-Hodgkins lymphoma and lung cancer agreed with findings from other previous related studies. However, this was thought to be the first study that reported an increased risk of melanoma in rheumatoid arthritis patients treated with methotrexate when compared to the general population. Researchers need to further study whether the findings are unique to Australia and its environmental factors. If further studies confirm a risk of melanoma with methotrexate use, perhaps skin cancer screenings (especially for rheumatoid arthritis patients taking disease-modifying antirheumatic drugs like methotrexate) will become an important consideration.

According to rheumatologist Scott J. Zashin MD, "Because the rheumatoid arthritis patients were on methotrexate, one does not know if the increased risk was due to rheumatoid arthritis or that the patients were on methotrexate. There are signals that indicate an increased risk of melanoma exists with the TNF blockers (Enbrel, Remicade, and Humira).

Hopefully more research will clarify that. Until then, it is a good idea for rheumatoid arthritis patients to get a regular skin exam."

In addition to treating rheumatoid arthritis, methotrexate is a treatment option for other conditions including:

The medicine is available as an injectable solution or as oral tablets. Methotrexate injection is given under the skin (subcutaneously). Oral methotrexate is available in 2.5 mg tablets. It's important to remember that the drug is administered once a week for arthritis. The medicine is not taken daily like most medications.

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