Neo-adjuvant Chemotherapy With Letrozole in Patients With Estrogen Receptor Positive/HER-2 Negative Breast Cancer

Inclusion Criteria:

• Pathologically proven breast cancer patients who are candidate of neoadjuvantchemotherapy with AC followed by Docetaxel

• Age: 19-70 years

• ER or PR positive ,cT2-3N0 or cT1-3/N+ M0 (ER-positive ≥1% nuclear staining byimmunohistochemistry , Allred score≥3 )

• Available FFPE tissue for biomarker study

• HER2-negative by ASCO/CAP guideline

• Patients who agree to adequate contraception

• ECOG scores of 0-2

• Normal or acceptable kidney, liver, cardiovascular, and bone marrow functions

• Patients who provide consent

Exclusion Criteria:

• Inflammatory breast cancer

• Distant metastasis

• Cerebral vascular accidents including transient ischemic attack

• Pulmanary thromboembolism or deep vein thrombosis with 6 months; however, patients whoreceived more than 6 weeks of anticoagulation within 6 months and remains asymptomaticare eligible.

• With a history of malignant tumor or complicated with other malignant tumors inaddition to breast cancer, except for non-melanoma skin cancer, curatively resectedearly gastric cancer, differentiated thyoid cancer < 1 cm, or other cured malignanttumor without recurrence for at least 3 years

• Ejection Fraction <55% by MUGA scan / Echo CG

• No available tissue for biomarker study

• Pregnant or lactating women

• Patients with other serious diseases or medical conditions: Pituitary adenoma,Malabsorption syndrome, Major resection of gastrointestinal tract, Corrected QTinterval > 480 msec, Congestive heart failure or unstable angina pectoris, myocardialinfarction, stent insertion, angioplasty, coronary bypass surgery, symptomaticperipheral artery disease within 6 months before the enrollment

• NYHA class III or IV congestive heart failure

• Uncontrolled hypertension and uncontrolled high-risk arrhythmia considered by theinvestigator

• Major surgery, major trauma, and/or unhealed wound, fracture, or ulcer within 4 weeks

• Acute hemorrhage or hemorrhagic tendency

• Obvious neurological or psychiatric disorders, including psychosis, epileptic dementiaand other diseases which may affect the understanding and sign of the informed consent

• Uncontrolled acute infection

• Patients with allergic constitution and any known or suspected drug allergy

• Concurrent use of other investigational drugs; or participating in other clinicaltrials involving investigational drugs within 30 days before this study

• Patients with mental illness or other conditions affecting the patient compliance

• Not suitable for the trial considered by the investigator