Select patients of primary breast cancer whose hormone receptor is positive and accepted postoperative adjuvant aromatase inhibitors for endocrine treatment.Treat them with zoledronic acid 4mg intravenous infusion every six months until the end of the aromatase treatment. Assess the disease-free survival; overall survival; combination of security, as well as the situation of bone loss.

The investigators select patients of primary breast cancer whose hormone receptor is positive and accepted postoperative adjuvant aromatase inhibitors for endocrine treatment.Treat them with zoledronic acid 4mg intravenous infusion every six months until the end of the aromatase treatment. Assess the disease-free survival; overall survival; combination of security, as well as the situation of bone loss.

Inclusion Criteria:

1. Karnofsky≥70

2. Provision of informed consent

3. Pathological confirmation of breast cancer

4. Hormone receptor-positive and accept aromatase inhibitors for adjuvant endocrine therapy

5. Not previously received treatment with bisphosphonate

6. Laboratory criteria:

   PLT≥100*109/L WBC≥4000/mm3 HGB≥10g/dl GOT,GPT,ALP≤2*ULN TBIL,DBIL,CCr≤1.5*ULN

7. Surgery , radiotherapy and chemotherapy has finished

Exclusion Criteria:

1. Pregnant of lactation woman
2. History of organ transplantation
3. With mental disease
4. With severe infection or active gastrointestinal ulcers
5. With severe liver disease (such as cirrhosis), kidney disease, respiratory disease or diabetes
6. Disease-free period of other malignant tumor is less than 5 years(except cured basal cell skin cancer and cervical carcinoma in situ)
7. With heart disease
8. Experimental drug allergy