INTRODUCTION: The efficacy of granulocyte colony-stimulating factors (G-CSF) in reducing febrile neutropenia (FN) risk is well established, but real-world data on trends in G-CSF use and its efficacy in recent years are lacking.
OBJECTIVES: To assess temporal trends in the use of G-CSF primary prophylaxis (PP) and risk of FN among elderly women receiving selected adjuvant chemotherapy regimens for early-stage breast cancer (ESBC).
METHODS: We identified women, aged greater than or equal to 66 years, with ESBC who initiated adjuvant chemotherapy using SEER-Medicare data from 2002 to 2012. Adjusted, calendar-year–specific proportions were estimated for use of G-CSF PP and FN risk in the first chemotherapy cycle, overall and stratified by G-CSF PP, using logistic regression models controlling for demographics and observable FN risk factors. Annual probabilities were estimated with covariates set to modal values.
RESULTS: Among 11,107 eligible patients, mean age was 71.7 years; 8,235 (74%) received G-CSF in the first course of chemotherapy; 5,819 (52%) received G-CSF PP; and 628 (6%) experienced FN in the first cycle. The adjusted proportion using G-CSF PP increased from 6.4% in 2002 to 71.2% in 2012. During the same period, the adjusted risk of FN in the first cycle increased from 2.0% to 3.0%. Figure 1 presents year-specific adjusted risk of FN by G-CSF status.
CONCLUSIONS: The use of G-CSF PP increased substantially during the study period. Although channeling of higher risk patients to treatment with G-CSF PP is expected, the adjusted risk of FN among patients treated with G-CSF PP tended to be lower than among those not receiving G-CSF PP.
