Accelerated AC regimen-Doxorubicin 60 mg/m2,Cyclophosphamide 600 mg/m2 on day 1 & day 14 of each cycle along with G-CSF support for up to 4 cycles, followed by Paclitaxel 175 mg/m2 in the next 4 cycles is the standard clinical practice in Vietnam for breast cancer, this regimen is to facilitate the dose-dense schedule, patients receive every-2-week therapy along with G-CSF support. the accelerated dose-dense schedule improve disease-free and overall survival among women with breast cancer .Primary objective of this study is to compare the efficacy and safety of Nanogen's Pegcyte and Roche's Neulastim for prevention of chemotherapy (Accelerated AC regimen)-induced neutropenia on breast cancer patients. Breast cancer patients scheduled to receive myelosuppressive chemotherapy (AC regimen) will be recruited in this trial. All eligible patients receive single subcutaneous injection of study drugs 24 hours after chemotherapy administration in each cycle for 3 consecutive cycles. Efficacy and safety assessments will be assessed based on the incidence of severe neutropenia in combination of temperature > 38.3℃ or sepsis or life threatening infection and incidence of serious adverse events.