(February 26, 2008 - Insidermedicine) Use of drugs called erythropoiesis-stimulating agents, or ESAs, to treat the anemia that can occur in some patients receiving treatment for cancer increases patients' risks of developing blood clots and even dying, according to research published in the Journal of the American Medical Association.

Here are some facts about the use of ESAs in patients with cancer:

•    Treatments for some cancers can lead to anemia, or a reduction in the number of red blood cells in the circulation.

•    Anemia can cause symptoms, most notably fatigue, which can impair patients' quality of life.

•    ESAs can help boost patients' red blood cells, but possibly at the expense of causing venous thromboembolism (VTE) a condition in which blood clots form inside the deep veins of the legs, travel through the bloodstream, and become lodged in certain organs, such as the lungs or brain, where they can cause significant damage.

Researchers out of the Northwestern University Feinberg School of Medicine analyzed data collected from over 50 trials involving 13000 patients that explored the rate of death in those with cancer using ESAs vs. a placebo to treat anemia. Another 8,000 patients from 38 trials were reviewed to examine the rate of VTE.

The analysis revealed that taking ESAs was associated with a 57% increased risk of developing VTE, compared with taking a placebo. The treatment also significantly increased patients' risk of dying.

Today's research demonstrates that ESAs, used to treat the symptoms of anemia that can sometimes arise in cancer patients, has some significant safety concerns when used in this manner. Not only does it increase the risk of developing blood clots in the deep veins, but it also increases patients' risk of dying.

For Insidermedicine in Depth, I'm Dr. Susan Sharma.