Effectiveness of darbepoetin alfa versus epoetin alfa for the treatment of chemotherapy induced anemia in patients with gynecologic malignancies

Abstract

Objective. Chemotherapy induced anemia (CIA) commonly occurs in gynecologic oncology patients. This often leads to treatment with erythropoietic stimulating agents in order to prevent chemotherapy delays, dose modifications and transfusion of red blood cells. Our objective was to determine the subsequent transfusion rates following administration of either darbepoetin alfa or epoetin alfa. Methods. A single institution retrospective chart review was performed utilizing patients from January 2003 to September 2004 who received either darbepoetin alfa or epoetin alfa for CIA (Hgb ≤ 10.0). Data collection variables included patient demographics, cancer diagnosis, chemotherapy treatment(s), laboratory data, erythropoeisis stimulation data, and transfusions. Sample size calculations were set to detect a 20% transfusion rate difference between the two groups. Chi-square, Fisher exact test and student t tests were used for statistical analysis. Results. 123 patients were eligible for analysis (60 darbepoetin alfa; 62 epoetin alfa). 93% of darbepoetin alfa patients received 200 mg every other week, while 86% of epoetin alfa patients received 40,000 U weekly. The darbepoetin alfa and epoetin alfa groups were similar in respect to age, race, tumor type, histology, previous chemotherapy, number of chemotherapy agents, weeks of erythropoietic stimulation, and baseline serum levels of creatinine and hemoglobin. The mean baseline Hgb and change in Hgb was similar for each group (darbepoetin alfa = 11.2, 2.5 and epoetin alfa = 11.3, 2.3). Twenty one (35%) of the darbepoetin alfa patients received a transfusion of packed red blood cells compared to 12 (19%) of epoetin alfa patients (p = 0.05). Conclusions. This retrospective analysis powered to detect differences in transfusion rates revealed a statistically significant difference in transfusion rates between darbepoetin alfa and epoetin alfa for the treatment of CIA. These data warrant a randomized prospective trial in gynecologic oncology patients with careful attention to the timing of initiation of treatment, dosing regimens, and titration of growth factor.