Anemia Drugs May Raise Blood Cancer Risk

By Julie Steenhuysen

CHICAGO DEC 10, 2007 (Reuters) - Erythropoiesis-stimulating drugs may increase the risk that patients with myelofibrosis will develop leukemia, U.S. researchers said on Monday.

The findings may heighten safety concerns over erythropoiesis-stimulating agents or ESAs. U.S. regulators last month strengthened safety warnings on the drugs amid concerns that they increase the risk of death, heart attack, stroke and the progression of other cancers.

Researchers at the Mayo Clinic in Rochester, Minnesota, examined the records of 311 patients with primary myelofibrosis from 1976 to 2006 to see what factors led some of them to advance to acute leukemia.

"We found an association with erythropoietin and erythropoietin like-drugs," said Dr. Ayalew Tefferi, who presented the study at American Society of Hematology"s annual meeting in Atlanta.

Dr. Tefferi said they also found a higher risk with the drug Danazol.

"The patients in the study who took the anemia drugs tended to be sicker. Their leukemia could have been caused by other factors," said Amgen spokeswoman Ashleigh Koss.

"It is important to remember that this is a retrospective study, not a prospective study," Koss said.

Dr. Tefferi agreed that a prospective study was needed, but until such studies could be performed, he said, patients taking the drugs should be carefully evaluated.

"The safety has to be proven," he said in a telephone interview.


"Reuters content is the intellectual property of Reuters Limited. Any copying, republication or redistribution of Reuters content, including by caching, framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in content, or for any actions taken in reliance thereon."