Study confirms clot risks with anti-anemia drugs

* Large study finds the drugs double clot risk

* No reduction in blood transfusions seen

By Julie Steenhuysen

CHICAGO, Nov 10 (Reuters) - Cancer patients who took drugs to cut the risk of anemia were twice as likely to develop blood clots in the lungs or legs as other patients, a decade-long study of more than 55,000 cancer patients has found.

The study adds to mounting evidence that the risks of the commonly used drugs -- known as erythropoiesis-stimulating agents or ESAs -- may outweigh the benefits.

ESAs stimulate bone marrow to increase the production of red blood cells. They were first approved in cancer patients in 1991 to reduce the number of blood transfusions needed during chemotherapy.

But despite widespread use of the drugs -- rising tenfold between 1991 and 2002 to nearly half of all cancer patients undergoing chemotherapy -- blood transfusion rates among these patients remained steady, Dr. Dawn Hershman of New York-Presbyterian Hospital/Columbia University Medical Center and colleagues reported on Tuesday in the Journal of the National Cancer Institute.

"We dramatically increased the number of patients that received these agents," Hershman said in a telephone interview. "In the entire time, the transfusion rate didn't change."

Sales of the drugs, including Amgen's (AMGN.O: Quote, Profile, Research) Aranesp and Epogen and Johnson & Johnson's (JNJ.N: Quote, Profile, Research) Procrit, have fallen sharply since a late 2006 study by J&J showed a higher risk of death and cardiovascular complications for aggressively treated patients.