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Erythropoiesis-stimulating agents: concern over patterns of use and risks

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Use of erythropoiesis-stimulating agents in US cancer patients undergoing chemotherapy has increased 10-fold since their introduction, yet there’s been no associated decline in the rate of blood transfusions, according to a study published today.

“It is also clear that when erythropoiesis-stimulating agents are given to cancer patients undergoing chemotherapy outside of the controlled setting of a clinical trial, there is (about) a twofold increased risk of venous thromboembolism,” Dr. Dawn L. Hershman, of Columbia University Medical Center, New York City, noted in an email to Reuters Health.

“There was concern from the beginning that thromboembolism may be a complication associated with these drugs,” she noted.

Using the Surveillance, Epidemiology and End-Results-Medicare database, Dr. Hershman and colleagues identified 56,210 patients aged 65 and older who received chemotherapy between 1991 and 2002. Of these, 15,346 (27%) received an erythropoiesis-stimulating agent.

According to a report in the November 10th online issue of the Journal of the National Cancer Institute, the proportion of patients treated with erythropoietin or darbepoetin increased from 4.8% in 1991 to 45.9% in 2002 (p < 0.001).

Despite this increase, the annual rate of blood transfusions was a constant 22% during the same time period, the report states. “Many of the patients in the study received both erythropoiesis-stimulating agents and blood transfusions over the course of their treatment,” Dr. Hershman told Reuters Health.

In addition, the records showed that venous thromboembolism developed in 14.3% of patients who received an erythropoiesis-stimulating agent compared to 9.8% of those who did not (hazard ratio, 1.93). Overall survival was no different in those who did and did not receive these drugs.

Erythropoiesis-stimulating agents, the authors note in their report, are of particular interest from a public policy standpoint because they’re so costly. “The total US sales of erythropoiesis-stimulating agents increased from $6.4 billion in 2002 to $10 billion in 2006, accounting for a greater Medicare Part B expenditure than any other drug,” they said.

“We speculate that this use was fueled by aggressive marketing to patients and physicians that focused on a promise of increased energy during chemotherapy treatment,” the researchers write.

This study, Dr. Hershman said, “stresses the need to continue to monitor new drugs for long-term safety. It is also important to make sure the benefits outweigh the risks.”

Reference:
J Natl Cancer Inst 2009.