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From Wednesday’s Globe and Mail
February 27, 2008 at 9:51 AM EST
Drugs commonly given to cancer patients because they are anemic after chemotherapy appear to increase their risk of dying, according to a new study.
The research, published in today’s edition of the Journal of the American Medical Association, suggests that the drugs, called erythropoiesis-stimulating agents (ESAs for short), may actually provide fuel to cancerous tumours.
“It’s troubling that 15 years after the drug came out, we finally came to this realization,” said Charles Bennett, an oncologist at Northwestern Memorial Hospital in Chicago and lead author of the study.
He said accepted practice is that using ESAs in moderation is safe but the new research challenges that view, “raising the concern that the drug may be stimulating cancer and shortening cancer patients’ survival.”
The new study is a meta-analysis, a compilation and analysis of previously published research. A total of 51 studies were included with 13,613 patients.
The analysis showed that patients who received ESAs to treat anemia had a 10-per-cent increased risk of death compared with cancer patients who did not receive the drugs.
Anemia is a common side effect of chemotherapy. Chemotherapy helps kill cancer cells, but it also eliminates good, healthy ones such as blood cells. It can decrease red blood cell levels, causing anemia and exhaustion.
Anemia can be treated with blood transfusions, but, in recent years, it has become common practice to treat the condition with one of two drugs, erythropoietin or darbepoetin, which stimulate production of red blood cells.
Last year, the U.S. Food and Drug Administration issued a public health warning about ESAs, particularly their use in cancer patients not undergoing chemotherapy.
Safety concerns are related to the fact that these drugs can cause life-threatening blood clots.
The new study confirms that concern, showing that patients receiving ESAs see their risk of blood clots in the legs or lungs jump by 57 per cent.
About 7.5 per cent of cancer patients treated with ESAs developed blood clots compared with 4.9 per cent who took placebos in the study. Dr. Bennett said that the increased rate of death does not appear to be due to blood clots, but rather by a return of cancer.
Another researcher involved in the study, Stephen Lai, an assistant professor at the University of Pittsburgh Medical Center, did laboratory work that showed cancer cells were stimulated when he exposed them to ESAs.
“We saw dramatic change,” he said. “Giving cancer patients EPO [a type of ESA] for their anemia may actually cause their tumours to progress.”
Dr. Bennett said he believes the findings should have an influence on clinical guidelines and oncologists should rethink their use in cancer patients.
“If I had cancer and needed a blood transfusion, I would be much more conservative about taking ESAs,” he said.
ESAs such as darbepoetin (brand name Aranesp) and erythropoietin (brand names Epogen and Procrit) are used to treat kidney disease as well as chemotherapy-related anemia.
According to the paper, ESAs generate sales of more than $6-billion (U.S.) annually in the United States.