(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 Hodgkin’s 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 hasn’t 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 body’s 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 year’s time -- it might not be justified.
