The purpose of this study is to evaluate the efficacy and safety of nab-PTX and trastuzumab for ER negative and HER2 positive operable (tumor size of 3cm or less and N0) breast cancer.

Inclusion Criteria:

1. Histologically confirmed invasive breast cancer
2. Tumor size of 3cm or less and N0
3. Hormone receptors have been identified as negative
4. HER2 positive confirmed by IHC 3+ or FISH+
5. LVEF > 50% by echocardiogram or MUGA
6. Adequate EKG
7. No prior treatment for breast cancer
8. PS 0-1
9. Required baseline laboratory data WBC > 4,000/mm3 and Neut > 2,000/mm3 PLT > 100,000/mm3 Hb > 9.0g/dl AST and ALT < ULNx2.5 T-Bil < 1.5mg/dl Serum creatinin < 1.5mg/dl
10. Written informed consent

Exclusion Criteria:

1. With history of hypersensitivity reaction for important drug in this study
2. With history of invasive breast cancer
3. Bilateral invasive breast cancer
4. Patients with medical conditions that renders them intolerant to primary chemotherapy and related treatment, including infection, diarrhea, intestinal paralysis, severe Diabetes Mellitus
5. Positive for HBs antigen or HCV antibody
6. With history of congestive heart failure, uncontrolled or symptomatic angina pectoris, arrhythmia or myocardial infarction, poorly controlled hypertension
7. With severe edema
8. With severe peripheral neuropathy
9. With severe psychiatric disorder
10. Pregnant or nursing women
11. The case that is judged to be unsuitable for this study by physician