Maintenance Hormone Therapy for Postmenopausal HR Positive Advanced Breast Cancer

Inclusion Criteria: Provision of informed consent Histologically proven HR positive breast cancer Postmenopausal woman, defined as a woman fulfilling any 1 of the following criteria (based on the NCCN definition of menopause \[National Comprehensive Cancer Network 2008\]): Prior bilateral oophorectomy Age ≥60 years Age \<60 years and amenorrheic for 12 or more months in the absence of chemotherapy, tamoxifen, toremifene, or ovarian suppression and follicle stimulating hormone and oestradiol in the postmenopausal range. Patients have completed first-line chemotherapy for metastatic breast cancer The first-line chemotherapy must be given to patients with visceral disease or progressive disease requiring a fast response Responded(CR or PR) or stabilized(SD\>=24 weeks) to first-line chemotherapy for metastatic breast cancer The duration of 1st line chemotherapy for advanced breast cancer had been at least 4 cycles and at most 8 cycles WHO performance status 0, 1 or 2- Exclusion Criteria: * Presence of life-threatening metastatic visceral disease, defined as extensive hepatic involvement, or any degree of brain or leptomeningeal involvement (past or present) Prior hormonal treatment for metastatic breast cancer are not allowed More than one line of cytotoxic chemotherapy for metastatic breast cancer Her-2 positive Other malignant tumor (concurrent or previous). Any severe concomitant condition which makes it undesirable for the patient to participate in the trial or which would jeopardise compliance with the study protocol, eg, uncontrolled cardiac disease or uncontrolled diabetes mellitus