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BACKGROUND: This retrospective study aimed to evaluate the efficacy of a 3.6-mg dose of pegfilgrastim for primary prophylaxis in Japanese breast cancer patients receiving dose-dense chemotherapy. METHODS: Patients treated with adjuvant or neoadjuvant chemotherapy for early-stage breast cancer at the Tokyo-West Tokushukai Hospital were included in this analysis. Because 6 mg pegfilgrastim has not yet been approved for use in Japan, we compared the outcomes of a dose-dense doxorubicin and cyclophosphamide regimen plus 3.6 mg pegfilgrastim support with a conventional dose epirubicin and cyclophosphamide regimen. The incidence of febrile neutropenia, relative dose intensity, dose delay, dose reduction, regimen change and hospitalization because of neutropenia were assessed. RESULTS: From November 2013 to March 2016, 97 patients with stage I-III invasive breast cancer were analyzed (dose-dense doxorubicin and cyclophosphamide plus 3.6-mg pegfilgrastim group, n = 41; epirubicin and cyclophosphamide group, n = 56; median ages, 49.0 and 48.5 years, respectively). Febrile neutropenia occurred during the first chemotherapy cycle in 7 of 56 patients (12.5%) in the epirubicin and cyclophosphamide group and 0 of 41 patients in the dose-dense doxorubicin and cyclophosphamide group (P = 0.02). The average relative dose intensities were 97.9% and 96.8%, respectively (P = 0.28), with corresponding dose delay rates of 4.9% (2/41) and 16.1% (9/56), respectively (P = 0.11) and dose reduction rates of 0% (0/41) and 7.1% (4/56), respectively (P = 0.16). CONCLUSIONS: Our results indicate the efficacy of a 3.6-mg pegfilgrastim dose for the primary prevention of febrile neutropenia in dose-dense doxorubicin- and cyclophosphamide-treated Japanese breast cancer patients.
Mizuno et al. (Fri,) studied this question.