Clinical Study of Adjuvant Therapy on Post-menopausal Women With Breast Cancer Under the Guidance of the Results of Preoperative Endocrinotherapy

Inclusion Criteria:

* Female, not more than 75 years old, judged to have been in menopause by the investigator when enrolled. Refer to the following criteria to determine whether they are postmenopausal breast cancer.

  * Spontaneous amenorrhea for more than 12 months Age ≥ 60 Age \< 60, but FSH and E2 reach postmenopausal level.
  * Received bilateral ovariectomy previously
  * Not to define the women using LHRH agonists or antagonists as in postmenopausal state.
* Evidence of primary invasive breast cancer is confirmed by histopathological diagnosis.
* Clinical stage is T2-3N0M0
* ER or PgR are expressed in more than 50 percent of tumour cells, and HER2 is negative.
* No abnormal axillary nodes in ultrasound examination; no evidence of cancer metastasis confirmed by abnormal lymph node puncture pathological examination
* With plan of receiving simple endocrinotherapy and avoiding adjuvant chemotherapy
* No previous breast cancer treatment history
* No other tumors previously; no unstable complications or uncontrolled infection.
* No contraindication for endocrinotherapy with 3rd generation of aromatase inhibitors
* Participate in the trial voluntarily and sign the informed consent form.

Exclusion Criteria:

* Evidence of distant breast cancer metastasis by pathological and imaging diagnosis
* Patients who have a history of other malignant tumors
* With contraindications for 3rd generation of aromatase inhibitors
* Physical condition can not bear the experiment
* Patients who have potential mental, psychological, familial, social, geographic, or other factors that can hinder study regime performance.
* Patients who were treated or are treated with other anti-tumor measures before or during this trial, or planed to participate in other clinical trials.
* Patients who refuse to participate in the trial.