People with cancer may develop a blood problem called anemia, due to the treatment or from the disease itself. They will have very low levels of healthy red blood cells, causing additional health problems. For years, doctors have tried to prevent or treat anemia with injections of erythropoiesis stimulating agents (ESAs) in order to spare cancer patients the many serious harms associated with a red-blood cell transfusion (such as hepatitis, transfusion-related acute lung injury, infection). Earlier reviews of the research showed that ESA treatment reduces the need for transfusion but, in recent years, several studies have shown that ESAs themselves cause harm. The drug may, for example, stimulate tumor growth and cause potentially fatal blood clots. In 2007, new studies reported that ESAs shortens survival in people with breast, non-small cell lung, head and neck, lymphoid and cervical cancers.

A new systematic review was needed to evaluate the old and the new evidence together and determine the impact of ESAs on survival in cancer patients to see if there are groups of patients who are at increased or decreased risk compared to the average. To accomplish this the authors of this meta-analysis conducted an in-depth assessment of the individual patient data generated by the care of nearly 14,000 patients from 53 trials conducted worldwide. Data on each of these patients were provided by three companies that make ESAs: Amgen, Johnson & Johnson, and Roche, and by several independent researchers. (The drug companies, however, had no role in conducting the meta-analysis.) The trials investigated one of two types of ESAs, epoetin or darbepoetin, and compared the use of one of these drugs plus red blood cell transfusion (as needed), with red blood cell transfusion alone (as needed). Most patients were given their treatment while undergoing anti-cancer therapy (chemotherapy and/or radiotherapy); but others received the treatment after they had completed their anti-cancer therapy. Some patients already had anemia; others were treated in order to prevent it. The patients had many different forms of cancer and many different anti-cancer treatments. 

The authors of this new meta-analysis concluded that ESA treatment shortens survival. They could not identify with certainty any subgroup of patients at either increased or decreased risk of dying when taking ESAs. With their doctors' help, cancer patients should consider the risks of taking ESA against the risks of a blood transfusion. Be aware, however, that uncertainties remain about the magnitude of each.