Real-World Impact of Granulocyte-Colony Stimulating Factor on Febrile Neutropenia

Background: Primary prophylaxis with granulocyte colony–stimulating factors (PP-G-CSF) is recommended in patients undergoing chemotherapy carrying a febrile neutropenia (FN) risk of 20% or more. In the present study, we examined clinical practice patterns and the impact of PP-G-CSF on FN incidence in women with early-stage breast cancer (EBC) treated with modern adjuvant chemotherapy (ACT). Methods: This single-centre retrospective cohort study of women with EBC, who were identified from the pharmacy database and who received at least 1 cycle of modern ACT from January 2009 to December 2011, was conducted at the Cancer Centre of Southeastern Ontario. Data on patient demographics, pathology, stage distribution, chemotherapy, PP-G-CSF use, dose reductions, chemotherapy delays, treatment discontinuation, relative dose intensity, and FN events were collected. Chi-square tests, t-tests, univariate and multivariate logistic regression analyses, and nonparametric Mann–Whitney U-tests were used for data analysis. Results: Of the 239 women eligible for analysis, 145 (61%) received PP-G-CSF, and 50 (21%) developed at least 1 episode of FN. Use of PP-G-CSF was associated with a significantly lower rate of FN (14% vs. 31%, p = 0.002) and trends to fewer dose delays (17% vs. 27%, p = 0.060) and dose reductions (19% vs. 25%, p = 0.28). Among women receiving PP-G-CSF, higher fn rates were associated with an age of 65 years or older, taxane-based chemotherapy, and prophylaxis with filgrastim. Conclusions: Clinical practice patterns at our institution showed that more than 50% of EBC patients treated with modern ACT received PP-G-CSF, which led to fewer FN episodes and increased delivery of planned ACT. The observed high FN risk despite PP-G-CSF was linked to older age, taxane-based chemotherapy, and filgrastim.