Impact of five prophylactic filgrastim schedules on hematologic toxicity in early breast cancer patients treated with epirubicin and cyclophosphamide

Purpose To evaluate the comparative efficacy of varying intensity schedules of recombinant human granulocyte colony-stimulating factor (G-CSF; filgrastim) support in preventing febrile neutropenia in early breast cancer patients treated with relatively high-dose epirubicin plus cyclophosphamide (EC). Patients and Methods From October 1991 to April 1994, 506 stage I and II breast cancer patients were randomly assigned to receive, in a factorial 2 x 2 design, epirubicin 120 mg/m(2) and cyclophosphamide 600 mg/m(2) intravenously on day 1 every 21 days for 4 cycles +/- lonidamine +/- G-CSF. The following five consecutive G-CSF schedules were tested every 100 randomly assigned patients: (1) 480 mu g/d subcutaneously days 8 to 14; (2) 480 mu g/d days 8, 10, 12, and 14; (3) 300 mu g/d days 8 to 14; (4) 300 mu g/d days 8, 10, 12, and 14; and (5) 300 mu g/d days 8 and 12. Results All of the G-CSF schedules covered the neutrophil nadir time. Schedule 5 was equivalent to the daily schedules (schedules 1 and 3) and to the alternate day schedules (schedules 2 and 4) with respect to incidence of grade 3 and 4 neutropenia (P =.79 and P =.89, respectively), rate of fever episodes (P =.84 and P =.77, respectively), incidence of neutropenic fever (P =.74 and P =.56, respectively), need of antibiotics (P =.77 and P =.88, respectively), and percentage of delayed cycles (P =.43 and P =.42, respectively). G-CSF had no significant impact on the delivered dose-intensity compared with the non-G-CSF arms. Conclusion In the adjuvant setting, the frequency of prophylactic G-CSF administration during EC could be curtailed to only two administrations (days 8 and 12) without altering outcome. This nonrandomized trial design provides support for evaluating alternative, less intense G-CSF schedules for women with early breast cancer.