Erythropoietin in Radiation Oncology – A Review

Abstract

The therapeutic potential of erythropoietin gains increasing attention among radiation oncologists because the prognosis is better for patients with high blood hemoglobin levels following radiotherapy. However, there is still a debate on how hemoglobin affects radiotherapy. Further, the means to manipulate the hemoglobin level, their indication and administration need to be clarified. Available experimental and clinical data on hypoxia, anemia and on their treatment with erythropoietin have been extensively discussed at an international conference in Freiburg, Germany, in June 1999. This report gives a summary reviewing the topic.

Pleiotrophic actions of erythropoietin

“…Correction of anemia, especially via the clinical use of Epo, also appears to be important in the outcome of radiotherapy treatments for cancer (54,55,56,57). Low hemoglobin levels, and associated low tissue oxygenation, causes a decrease in radiosensitivity of tumor cells (54,58,59,60).…”

Erythropoietin inhibits apoptosis induced by photodynamic therapy in ovarian cancer cells

“…Studies of patients with head and neck cancers (3), lung cancer (4), and pelvic malignancies (5), whose anemia has been corrected, or prevented, through the administration of erythropoietin have been reported to experience improved local/regional tumor control, quality of life, and survival in comparison with patients undergoing radiotherapy in the presence of anemia or whose anemia was partially corrected through the use of blood transfusions. Correction of anemia, especially with erythropoietin, also has been reported to be important in the outcome of radiotherapy and photodynamic therapy (PDT) treatments of cancer (3,6). In a phase II trial of patients whose metastatic renal cell carcinoma was progressing on interleukin-2, results suggested that erythropoietin administration decreased interleukin-2 treatment toxicity, prevented drops in hemoglobin levels, and appeared to counteract the interleukin-2 -driven increase in vascular endothelial growth factor levels, thereby inhibiting angiogenesis (7).…”

Effect of the Hypoxic Cell Sensitizer Isometronidazole on Local Control of Two Human Squamous Cell Carcinomas after Fractionated Irradiation

“…Possible approaches include correction of anemia by transfusion [9] or erythropoietin [17,41], application of hyperbaric oxygen or normobaric carbogen [36,38], application of drugs that improve tumor perfusion [22], and use of hypoxia-specific cytotoxins [8,10]. Another possibility that has been widely tested in experimental and clinical studies is the use of electron-affinic substances, so-called hypoxic cell sensitizers.…”