The negative impact of anemia on radiotherapy and chemoradiation outcomes

In cancer patients, anemia is common and has been found to impair quality of life and reduce locoregional disease control conferred by radiotherapy. The prognostic importance of anemia in the radiation oncology setting may be related to a reduction of molecular oxygen levels, thereby attenuating radiation-induced damage and ultimate cell death. Substantially higher doses of radiation are required to eradicate malignant cells under the hypoxic conditions commonly identified in solid tumors. Consistent with this, patients with hypoxic solid tumors have been found to have shorter postradiation disease-free survival rates relative to patients with well-oxygenated tumors. An attempt to enhance intratumoral oxygenation via correction of anemia, a highly prevalent but modifiable condition, is therefore a reasonable approach to optimize radiotherapy and chemoradiation outcomes. Clinical studies investigating recombinant human erythropoietin (epoetin alfa) as an adjunct to radiotherapy have demonstrated its ability to increase and maintain hemoglobin (Hb) levels during the course of radiotherapy. In a study involving anemic patients undergoing chemoradiation for head and neck cancer, epoetin alfa extended locoregional control and survival to rates reported for patients with normal pretreatment Hb levels. Given the high prevalence and prognostic significance of anemia during radiotherapy, strategies that safely and effectively increase Hb levels may be of value for optimizing radiotherapy and chemoradiation outcomes.