OBJECTIVES: To understand current utilization patterns, this study examined real-world treatment patterns and treatment costs for epoetin alfa (EPO) and darbepoetin alfa (DARB), two erythropoietic stimulating agents (ESA), as well as red blood cell (RBC) transfusion requirements in cancer patients. METHODS: Analysis of medical claims between 1/2004 and 2/2006 from the Integrated Health Care Information Services (IHCIS) national database from over 35 health plans nationwide was conducted. Patients included were ³18 years old, had ³1 claim for cancer within 90 days prior to treatment initiation, were newly initiated on EPO or DARB, and received ³2 doses. Mean cumulative ESA dose was used to calculate drug cost (based on 9/2006 WAC) and dose ratio (Units EPO:mcg DARB). The proportion of patients transfused during treatment was compared between the two groups. RESULTS: A total of 4008 EPO and 3039 DARB patients formed the study population. EPO patients were older (60.4 vs. 58.4 years, p<.0001) and a lower proportion were women (63% vs. 67%, p=.0006), compared to DARB patients. Mean treatment duration was similar for both groups (EPO: 58 days; DARB: 57 days; p= .3690). Mean (SD) cumulative dose administered was 278,783 (259,569) Units for the EPO group and 1118 mcg (949) for the DARB group, resulting in a dose ratio of 249:1 (Units EPO:mcg DARB) and significantly higher drug cost in the DARB group (EPO $3393, DARB $4971, p<.0001). RBC transfusion was administered to 6.1% of EPO patients compared to 8.0% of DARB patients (p=.002). CONCLUSION: This observational study of over 7000 cancer patients reported a dose ratio of 249:1 (Units EPO: mcg DARB), 46% higher DARB drug cost, and significantly higher transfusion rate in the DARB group compared to the EPO group. These findings provide greater understanding of current real-world ESA utilization in the managed care setting and corroborate earlier findings in this population.