Temporal and Geographic Variations in the Receipt of Colony-Stimulating Factors and Erythropoiesis-Stimulating Agents in a Large Retrospective Cohort of Older Women With Breast Cancer From 2000 to 2009

The purpose of this study was to use the most recent national data for a large cohort of patients diagnosed with breast cancer to evaluate temporal trend of receiving hematopoietic growth factors from 2000 to 2009 and to examine significant factors associated with increasing trends and geographic variations. We identified 26,130 women aged 65-89 years who were diagnosed with breast cancer and received chemotherapy in 2000-2009 from the Surveillance, Epidemiology, and End Results (SEER)-Medicare data. Colony-stimulating factors (CSFs) were identified if there was a claim from the following procedure codes: filgrastim, pegfilgrastim, or sargramostim. Erythropoiesis-stimulating agents (ESAs) were identified if there was a claim from the following procedure codes: epoetin or darbepoetin. Overall, 51.7% of patients with breast cancer received CSFs, which increased from 21.7% in 2000 to 63.2% in 2009. The percentage of patients receiving pegfilgrastim increased from 2.7% in 2000 to 19.5% in 2003 and then continuously to 49.7% in 2009. The overall percentage of patients receiving ESAs was 39.3%, which increased from 26.4% in 2000 to 60.8% in 2006, and then decreased significantly from 40.7% in 2007 to 12.9% in 2009. The receipt of both CSFs and ESAs differed significantly across different geographic areas. The receipt of CSFs continued to increase from 2000 to 2009, and pegfilgrastim started to replace filgrastim since 2003. The receipt of ESAs increased until 2006 and then declined substantially due to the black box warning. There were substantial geographic variations in the use of these hematopoietic growth factors.