A Study to Evaluate the Efficacy, Safety and Immunogenicity of Leucostim® Versus Neupogen® in Breast Cancer Patients

Inclusion Criteria: 1. Willing to provide a written informed consent 2. Men or women ≥ 18 and ≤ 70 years of age 3. Histologically or cytologically confirmed breast cancer (Stage II to Stage IV) 4. Be scheduled to receive TAC regimen as adjuvant therapy 5. Subjects who meet the conditions at screening test as follows; * Absolute Neutrophil Count (ANC) ≥ 1,500/mm3 * Platelet Count ≥ 100,000/mm3 * ECOG Performance Status : 0\~2 6. Adequate renal function (Creatinine ≤ 1.5 x ULN at screening test) 7. Adequate hepatic function at screening test (Total bilirubin/AST/ALT ≤ 1.5 x ULN, ALP ≤ 2.5 x ULN at screening test) Exclusion Criteria: 1. Prior chemotherapy experiences 2. Prior bone marrow or stem cell transplantation 3. History of treatment with hematopoietic growth factors (e.g. G-CSF, peg-G-CSF, erythropoietin) 4. History of prior malignancy other than breast cancer or surgically cured malignancies within 5 years of informed consent date 5. Participation in any other clinical study within 4 weeks of informed consent date or planning to simultaneously participate in another clinical study 6. Currently receiving radiation therapy or having completed radiation therapy within 4 weeks of informed consent date 7. Active infection which may require systemic antimicrobial or antiviral therapy during the study (e.g. ANC ≥ 12,000/mm3 or Body Temperature \> 38.2 degrees C (100.8 degrees F)) 8. History of systemic antibiotic use within 72 hours prior to chemotherapy 9. History of hypersensitivity to the investigational product, components or similar products 10. HIV positive 11. Pregnant or lactating women, or women of child-bearing potential who are not willing to follow a reliable and effective contraceptive measure during the course of the study and for at least one month after the completion of the study 12. Any other cases that is considered by the investigator as an exclusion