Reduced Dose of Pegfilgrastim as Support for Chemotherapy for Breast Cancer

Inclusion Criteria: * female aged 18-69 years * diagnosed pathologically as early breast cancer * with indication for adjuvant chemotherapy and suitable for AC regimen (epirubicin and cyclophosphamide, or pirarubicin and cyclophosphamide, planned chemotherapy with taxanes after AC regimen were allowed) * received no prior chemotherapy (chemotherapy naïve) * have Karnofsky performance status ≥ 80, * baseline hemoglobin ≥90g/L, white blood cell count ≥4.0X10\^9/L,ANC≥2.0X10\^9/L, platelet count ≥100X10\^9 * adequate cardiac, hepatic and renal function Exclusion Criteria: * enrolled onto or had not yet completed other investigational drug trials * allergic to any component of PEG-rhG-CSF injection, or other biological products derived from genetically engineering Escherichia coli; * pregnant or lactating women; * previous large volume radiotherapy, or prior bone marrow or stem-cell transplantation