"These agents were approved to reduce the risk of blood transfusions by 50 percent," Hershman said. "There was absolutely no difference in the transfusion rate over the 10-year period from when these drugs hit the market," she said. "The majority of patients are getting these drugs and receiving transfusions."
Based on concerns raised by earlier studies, the U.S. Food and Drug Administration in 2007 required a black box warning label on ESAs about the risk for venous thromboembolism, tumor promotion and death. The warning suggested restricting the use of ESAs to specific tumor types, and addressed dosage, duration and targeted hemoglobin levels.
In 2006, U.S. sales of ESAs were $10 billion and accounted for the largest Medicare expenditure for any drug.
Hershman thinks the findings raise questions about the drug's approval process and whether adequate post-marketing research was undertaken to ensure their long-term safety.
These drugs do have a place, she said. "But we have to figure out what the best indication is and use every agent with caution. We should think about the drugs that we give."
Dr. J. Leonard Lichtenfeld, deputy chief medical officer at the American Cancer Society, said that "this study is one more in a list of several that suggests the value of ESAs was less than originally hoped, and the side effects were greater than previously understood."
Patients and doctors should be aware of all the risks and benefits before using the drugs, he said.
"If you are going to be treated with these drugs, do so with caution, do so with understanding, have a discussion with your physician about the need for these drugs and what the potential difficulties may be," he said.
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