Drug To Treat Anemia In Cancer Is Harmful
A new review of data confirms that erythropoietin — a drug to treat anemia in many cancer patients — might be harmful. The review found that patients with head and neck cancers who received erythropoietin in combination with radiation had poorer outcomes than those who received radiation treatment alone.
The review appears in the latest issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
Severe anemia in cancer patients can lead to decreased oxygen supply to tumor cells. A lower level of oxygen in tumor cells is associated with more rapid tumor progression and a poorer response to therapy. Many use erythropoietin, or EPO, a hormone that controls red blood cell production, to correct anemia.
“It has therefore been thought logical that using erythropoietin to correct anemia before or during chemotherapy, radiotherapy or both would improve prognosis,” the review authors write.
Dr. Philippe Lambin and colleagues at the MAASTRO (Maastricht Radiation Oncology) Clinic in the Netherlands conducted the review.
The investigators analyzed data from five published clinical trials that looked at whether combined radiation and EPO was better than standard radiation therapy alone in the treatment of head and neck cancers. Nearly 1,400 patients were included in the analysis. The researchers compared overall survival, the length of time during and after treatment in which the cancer did not progress, local tumor control and toxicity in the two different treatment groups.
Researchers found that patients who received EPO had significantly worse overall survival compared to patients who did not receive the drug. In addition, patients who took EPO had significantly shorter times before their cancers worsened.
Data included in the review suggest that decreased survival rates in cancer patients who took EPO were not due to some toxic effect of the drug itself, such as an increase in deaths due to blood clots. Instead, researchers have hypothesized that the drug might actually cause some types of tumors to grow.
Barbara Burtness, M.D., chief of the Head and Neck Medical Oncology division at the Fox Chase Cancer Center in Philadelphia, commented on the use of erythropoietin in head and neck cancer.
“The primary use of erythropoietin in cancer patients is to raise hemoglobin when patients become anemic, either because of the cancer or because of a side effect of the cancer treatments,” she said. “It’s been a part of practice for a long time.”
Burtness said that there has been a specific reason for studying EPO in head and neck cancers. “When radiation treatments are given for bulky cancers in the head and neck area, it’s thought that cancer cells that don’t have a high oxygen content are less susceptible to being killed by radiation. The hypothesis has been that if you could correct a patient’s anemia, there would be more red blood cells traveling to the area of cancer. This would lead to correction of the low oxygen content in the tumors — and the patient would be more likely to respond to the radiation treatment,” she said.
“But what we’ve been hearing for some time is that erythropoietin is actually making cancer outcomes worse,” she said.
She said the United States has tightened guidelines EPO use in response to data from recent studies. “Giving erythropoietin can have a negative impact on survival. We certainly are not using it here [at Fox Chase Cancer Center]. Among our patients who’ve received radiation elsewhere, its use does not appear to be common.”
Manufacturers promoted EPO to improve anemia, and to help anemic patients to feel better overall. However, the U.S. Food and Drug Administration has issued several public health advisories underscoring the possible risks of using EPO in cancer, including faster tumor growth and early death. The FDA warnings also say that EPO does not improve symptoms associated with anemia, such as fatigue. Nor does EPO improve a patient’s quality of life or sense of well-being, the advisories say.