Common Rheumatoid Arthritis Drug Won't Raise Blood Cancer Risk

By Carolyn Colwell
HealthDay Reporter
Friday, February 29, 2008; 6:00 PM

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FRIDAY, Feb. 29 (HealthDay News) -- Methotrexate, one of the most common drugs used to ease rheumatoid arthritis symptoms, will not raise a patient's risk for blood cancer, a new study finds.

But a lesser-used medicine, cyclophosphamide, was associated with a doubling in patients' odds for lymphoma, the Canadian researchers found.

The study of almost 24,000 patients over 23 years of age showed no clear association between methotrexate and cancers of the blood, such as lymphoma. Methotrexate has been long and widely used by many patients with rheumatoid arthritis.

There was an elevation in cancer risk with cyclophosphamide, which is sometimes used to treat very severe rheumatoid arthritis that has progressed to the point of threatening or damaging organs.

The results, "add to the literature regarding the cancer risk associated with cyclophosphamide and emphasizes that we need to continue to develop safer drugs for very severe forms of autoimmune disease," said study lead author Dr. Sasha Bernatsky, an epidemiologist at McGill University in Montreal. Her team published its findings in the Feb. 25 issue of the Archives of Internal Medicine.

Bernatsky added that it is important to recognize with cyclophosphamide that "even though the risk of certain cancers in some autoimmune disease is elevated, these cancers are still relatively rare -- much less than 1 percent. People should not stop taking their drugs if their specialists really feel that they need these drugs."

Bernatsky said such patients need to, "keep in mind that cyclophosphamide has been demonstrated to have overall benefits in some cases, such as preserving kidney function when kidneys are affected by autoimmune disease."

Rheumatoid arthritis, which affects an estimated 1.3 million Americans, is a chronic inflammatory disease in which the body's autoimmune system most commonly attacks the joints, according the Arthritis Foundation. According to the study, over the past 30 years, doctors have noted an increased risk for lymphoma in patients with rheumatoid arthritis, although the exact reasons for that phenomenon remain unclear.