Arthritis Drug Linked to Lymphomas
Reported November 24, 2004
(Ivanhoe Newswire)–A new study helps explain why a drug commonly used to treat rheumatoid arthritis and polio increases the risk of lymphoma linked to the Epstein-Barr virus.
The authors explain Epstein-Barr is a common virus, present in about 90 percent of the adult population. The virus sets up a lifelong infection that has been linked to several diseases, including mononucleosis and Hodgkins disease. But in most people, the infection remains latent, meaning it causes no harm.
Doctors have known the drug methotrexate increases lymphomas that test positive for the Epstein-Barr virus, but it hasnt been clear how the medication leads to the condition. In this study, the investigators looked at the effect of the drug on cell lines infected with the virus. Results showed the drug reactivated the virus from latent infections, leading to the release of infectious agents into the body.
Since methotrexate is an immunosuppressive drug, which means it causes the immune system to work less well than it normally would, researchers speculate a deadly combination effect is at work: The drug both reduces the bodys ability to fight off the cancer and makes it possible for the virus to invade the body and help create the cancer.
The investigators report the drug acyclovir (Zovirax) might be able to reduce the number of lymphomas caused by methotrexate, but note the overall risk of developing lymphoma due to the drug is so low — less than 1 in 1,000 patients on the medication will be affected in a years time — it might not be justified.
SOURCE: Journal of the National Cancer Institute, 2004;96:1691-1702