Patient description: The patient is a 42 year-old postmenopausal woman who had a screening sonogram which revealed an abnormality in the right breast. She had no palpable masses on breast exam. Core biopsy was done and revealed a 1.8 cm infiltrating ductal breast carcinoma in the left upper outer quadrant. Lumpectomy was done and the surgical margins were clear. The tumor was HER2-positive and ER/PR negative. Axillary sampling revealed 1 positive lymph node out of 12 sampled. CXR was unremarkable. She is using “well women” multivitamins daily and no other medication. She smokes frequently and consumes alcohol occasionally. She is in a relation with only one partner and has a history of 3 pregnancies and live births. She breastfed all three children.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Breast Cancer All patients must have signed and dated an informed consent form 2. Patients must be female 3. Primary invasive breast cancer pathologically approved by core needle or open biopsy 4. Ipsilateral axillary or internal mammary nodes positive, or tumor size is equal to or larger than 4cm. Definition of nodes positive is according to the staging system of AJCC 6th edition (American Joint Cancer Commission) for breast carcinoma. The micrometastasis must be at least 0.2mm 5. Patients must have undergone standard surgery for primary breast cancer as shown in the following a standard radical mastectomy or modified mastectomy standard breast conservation surgery (BCS), which is lumpectomy or qaudrantectomy accompany with axillary dissection, and the surgical margins of the resected specimen must be negative. BCS must be followed by standardized adjuvant radiotherapy to the partial conserved breast (delivered after adjuvant chemotherapy completed) Treatment for confirmed breast cancer including the surgery modality listed above, loco-regional radiotherapy after lumpectomy, adjuvant radiotherapy to the chest wall and/or internal mammary nodes and/or supraclavicular lymph nodes, adjuvant chemotherapy 6. adjuvant endocrine therapy of TAM or Fareston must be started within 6 weeks when adjuvant chemotherapy or radiotherapy was finished 7. The date of randomization must be processed after taking TAM or Fareston for 2 or more than 2 years, but not more than 3 years of time 8. Patients taking neo-chemotherapy are eligible, and lymph node status could be identified during surgery before neo-adjuvant chemotherapy or after neo-adjuvant chemotherapy. The definition of lymph node positive is evaluation of lymph node status before neo-adjuvant chemotherapy must pathological axillary nodes, internal mammary nodes (pN2b option) or supraclavicular nodes (pN3c option) involved. Micro-metastasis (i.e.≥0.2mm, pN1-pN3c) can be identified by the following method: fine needle aspiration (FNA) or sentinel node biopsy (SNB) or sampling/ total procedure of axillary dissection patients with no nodes positive after neo-adjuvant chemotherapy, lymph node positive must be evaluated during surgery. Its definition was the either of following According the clinical practice guidelines of the local cancer center, it is acceptable when positive nodes was identified by SNB or axillary dissection There is pathological evidence in lymph nodes positive (pN1-pN3c) during breast surgery after neo-adjuvant chemotherapy 9. Patients diagnosed as occult breast cancer clinically are found to pathologically have primary invasive carcinoma or DCIS with micro-invasive lesion in ipsilateral breast, and primary lesion or axillary node metastasis express ER and/or PR positive 10. Patients with synchronous bilateral cancers are eligible on the condition that If one side is IDC and the other side is DCIS, the IDC side should be of the ER and/or PR positive phenotype and IF two sides are both IDC, they must be ER and/or PR positive phenotype at the same time 11. Hormone receptor positive (≥＋) is defined as detecting ER or PR expression at any time is eligible. The situation of only PR positive and ER negative is eligible, too 12. According to the standard operation principles for clinical practice of local cancer center, patients must be randomized within 4 weeks after definitive physical examination, imaging examination and laboratory testing show no evidence of recurrence or metastasis 13. Based on the study objective, all patients are required to be premenopausal as defined by menstruating actively less than 6 months since last menstrual period (LMP), or patients younger than 40 years of age who became amenorrheic not more than 1 year if the serum free E2、FSH and LH level was premenopausal (according to the reference value of local center)  patients with metastatic malignant tumor 2. previous history of asynchronous bilateral breast cancer 3. any previous malignancy in the past 5 years, except for those treated with curative intent, such as carcinoma in situ of the cervix, squamous carcinoma of the skin or basal cell carcinoma of the skin 4. any non-malignant systemic disease which interfere long time follow up 5. history of medical ovarian ablation therapy 6. history of AI therapy 7. severe live dysfunction, Child-Pugh is grade C 8. Occult breast cancer is found pathologically no IDC lesion or only DCIS without micro-invasive lesion in the ipsilateral breast 9. patients with Her-2 overexpression had used, or is using, or intending to use adjuvant trastuzumab 10. severe heart dysfunction, heart functional classification is above Class III Table 2 Child-Pugh score of hepatic cirrhosis