Efficacy and Safety of 4.5mg PEG-rhG-CSF Per Cycle in Preventing Neutropenia After Intensive Chemotherapy for Breast Cancer

Inclusion Criteria: * Breast cancer patients in need for adjuvant chemotherapy confirmed by histopathology, whom should accept ddEC regimen. * ECOG\<=1 * Expected survival is greater than 6 months * Qualified for chemotherapy，WBC\>=3\*109/L, ANC\>=1.5\*109/L, Hb\>=80g/L, PLT\>=80\*109/L. With no bleeding tendency or systemic hematology disorder symptoms. * No obvious EKG abnormality, no obvious cardiac dysfunction, and normal left ventricular ejection fraction. * Liver function, ALT and AST should less than 2.5 times of the upper limit. * Renal function, Cr and BUN should less than 1.5 times of the upper limit. * Subjects voluntarily participate in this study and sign informed consent. Exclusion Criteria: * Total amount of doxorubicin used in previous chemotherapy\>240mg/m2, or epirubicin\>360mg/m2 * Has received hematopoietic stem cell transplantation or bone marrow transplantation * Other drugs are currently in clinical trials * There are currently hard-to-control infections, body temperature is higher than 38 degrees. * Received PEG-rhG-CSF treatment before enrollment * Received chemotherapy in 4 weeks before enrollment * Patients with any visceral metastasis * Patients with severe heart, kidney, liver or any other important organs chronic diseases * Patients with severe uncontrolled diabetes * Patients with allergic diseases, or allergies to this product or other biological products derived from genetically engineered e. coli * Suspected or real drug users, substance abusers, alcoholics * Pregnant or lactating women * Severe mental or neurological disorders that affect informed consent and adverse reactions described or observed