Study shows anemia drugs worsen death risk

Treating cancer patients with anemia drugs increases their risk of blood clots and death, U.S. researchers said, confirming concerns about these widely used drugs.

Researchers said the drugs, erythropoiesis-stimulating agents or ESAs, raise the risk of death by 10 percent in patients who took them compared to those who did not, a finding that could not be explained by the higher blood clot risk alone.

Anemia is a common complication of cancer treatment.

"The findings of mortality are new and are different from prior reports," said Dr. Charles Bennett of Northwestern University. The study appeared in the Journal of the American Medical Association.

He said the drugs also increased the risk of blood clots in the lungs and legs by 57 percent in cancer patients, confirming other findings.

"Our findings, in conjunction with basic science studies, raise the concern that the drug may be stimulating cancer and shortening cancer patients' survival," Bennett said in a statement.

Millions of cancer and kidney disease patients take ESAs, man-made versions of a human hormone called erythropoietin. They work by stimulating production of oxygen carrying red blood cells.

Drugs in the class include Amgen Inc's biggest drug Aranesp, and an older version, Epogen, and Johnson & Johnson's Procrit. The study sent shares of both companies lower in extended-hours trading on Monday.

Amgen spokeswoman Ashleigh Koss said the analysis does not define any new risks associated with ESAs, and the blood clot risk is included in current labeling.

She said doctors and their patients need to weigh the drugs' benefit -- avoiding a blood transfusion -- and the risks and use the drug appropriately.