Purpose: The goal of chemotherapy for metastatic breast cancer (MBC) is palliation of symptoms while minimizing treatment-related toxicities. It remains unclear whether use of granulocyte colony-stimulating factor (G-CSF) to maintain relative dose intensity of chemotherapy for MBC is associated with improved clinical outcomes.
Methods: The medical records of MBC patients treated with chemotherapy in 1st-3rd-line settings between May 2010 and April 2014 were reviewed. Time to progression (TTP), progression-free survival (PFS), and overall survival (OS) were compared between patients who received G-CSF and those who did not. Antibiotic use, total clinic visits, and pre- and post-treatment Eastern Cooperative Oncology Group (ECOG) performance status were also compared between the groups.
Results: Of the 169 patients included, 55 (32.5%) received > 1 G-CSF dose and 114 (67.5%) did not receive any G-CSF. The median TTP was similar between the two groups (5.0 months (95% CI 3.4-7.1) vs. 5.2 months (95% CI 4.8-6.2) respectively; p = 0.998). The median PFS (p = 0.955; 5.0 months (95% CI 3.4-5.9) vs. 5.2 months (95% CI 4.7-6.0), respectively) and OS (14.6 (95% CI 9.0-26.6) vs. 18.5 months (95% CI 15.2-22.0) in G-CSF and non-G-CSF groups, respectively; p = 0.628) were also similar between groups. No significant between-group differences were noted in rate of decline in ECOG performance status, antibiotic use, and number of clinic visits and hospitalizations.
Conclusion: This retrospective analysis did not find any evidence that the use of G-CSF to maintain chemotherapy dose intensity for the treatment of MBC improves TTP, PFS, and OS or results in improved ECOG performance status compared with lack of G-CSF use in patients with MBC treated in 1st to 3rd-line settings.
Keywords: Granulocyte colony-stimulating factor; Hematologic toxicities; Metastatic breast cancer; Palliative chemotherapy; Retrospective studies; Survival analysis.