US researchers said that treating cancer patients with anemia drugs increases their risk of blood clots and death, especially if given in the wrong doses, according to media reports Wednesday.

The study culled data from 51 clinical trials with 13,611 patients who were treated with erythropoiesis-stimulating agents (ESAs) or a placebo. The result found that ESAs increase the risk of death by 10 percent and the risk of blood clots known as venous thromboembolisms (VTE) by 57 percent.

Anemia is a common complication of cancer treatment. ESAs work by stimulating the bone marrow to produce new red blood cells. Millions of cancer and kidney disease patients take ESAs.

The drugs were first approved by the U.S. Food and Drug Administration in 2003 as a treatment for anemic cancer patients to avoid blood transfusions.

However, a report in 2006 said that no link was found between the deaths and Anemia drug uses among cancer patients.

"The current FDA recommendation is these drugs are safe for cancer patients as long their hemoglobin levels aren't raised too high. Our data do not support that," said Dr. Charles Bennett of Northwestern University in Chicago. "Patients should be informed of the risks and benefits of these drugs."

Amgen, a producer of Aranesp in this class, said doctors and their patients need to weigh the drugs' benefit and the risks and use the drug appropriately.

J&J, the producer of Procrit, said the study's conclusions "do not provide an accurate reflection of the safety profile" of ESAs when used to treat chemotherapy-induced anemia.

The FDA's Oncologic Drugs Advisory Committee plans to review on March 13 recent study results regarding the use of ESAs.

(Xinhua News Agency February 27, 2008)