The purpose of the study is to evaluate the efficacy and safety of PEG-rhG-CSF in patients with breast cancer who were treated with intensive chemotherapy for prevention of neutrophil reduction.

Inclusion Criteria:

1.18-65 years old, gender no limited.

2.Breast cancer diagnosed by pathology.

3.Did not receive chemotherapy previously and plans to receive 4 cycles intensive EC (epirubicin, cyclophosphamide) treatment.

4.No obvious blood system disease, ANC(absolute neutrophil count)≥ 1.5 × 10^9/L, PLT（Platelet）≥80×10^9 /L, Hb（hemoglobin）≥75g/L, WBC（White blood cell ）≥3×109/L, and no bleeding tendency.

5.KPS (Karnofsky performance status) score≥70.

6.Expected survival≥3 months.

7.Written informed consent are acquired.

Exclusion Criteria:

1. Severe or uncontrolled infection.
2. Sensitive to the product or other genetically engineered biological products from Escherichia coli strains.
3. Mental or nervous system disorders.
4. Severe heart, lung and central nervous system disorders.
5. Pregnant or lactating women.
6. TBIL(total bilirubin ), ALT（alanine aminotransferase）,AST（glutamic-oxalacetic transaminase） > 2.5×ULN（upper limit of normal）; if it were caused by liver metastases, TBIL, ALT,AST >5×ULN.
7. Cr（creatinine） >1.5×ULN.