An increased death rate was found to be associated with the drugs used by millions of cancer patients to fight against anemia by enhancing the red blood count. Researchers at Northwestern University's Feinberg School of Medicine gave these findings
The FDA approved drugs, called to boost their red blood cells and health, can do so by possibly stimulating the growth of cancer cells.
The finding came to light after a meta-analysis of 51 trials involving a total of 13,613 patients.
The research team found that cancer patients who took ESAs had a 10 percent increased risk of death as compared to those patients who kept away from the drugs.
"The FDA says if you use the drug in moderation, it should be safe. But our findings, in conjunction with basic science studies, raise the concern that the drug may be stimulating cancer and shortening cancer patients' survival," said Charles Bennett, M.D., the lead author of the study.
"It's troubling that 15 years after the drug came out, we finally came to this realization.
"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," he added.
Dr Stephen Lai, one of the study's co-authors who tested the response of cancer cells to an ESA called erythropoietin in the laboratory, said that the tests had shown that the dugs had a significant effect.
"We saw a dramatic change. Adding 'epo' (erythropoietin) to the cells increased their ability to migrate or invade. Our basic science findings and the clinical trial results suggest that giving cancer patients 'epo' for their anemia may actually cause their tumors to progress," he said.
The study also confirmed a previously known 57 percent increased risk of blood clots in the legs or lungs for cancer patients receiving ESAs.
Lai cautioned that various solid tumors such as breast cancer, colon cancer and melanoma may react differently to ESAs.
"The exact effect and size of that effect may be different depending upon the type of tumor. Additional research is clearly necessary, and we have to be careful about generalizing these results before further research is conducted," he said.
The study and its findings will be published in the Journal of the American Medical Association Wednesday, February 27.