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/m2 and cyclophosphamide 600 mg/m2 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 microg/d subcutaneously days 8 to 14; (2) 480 microg/d days 8, 10, 12, and 14; (3) 300 microg/d days 8 to 14; (4) 300 microg/d days 8, 10, 12, and 14; and (5) 300 microg/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.