Inclusion Criteria:

• Histologically confirmed metastatic adenocarcinoma of the breast (seeTNM staging Appendix I) that is ER and/or PR positive as determined in local laboratories at each investigator site (central verification of ER status will be performed after the patient starts treatment
• A tissue block from either the metastatic or primary tumor site is required.
• WHO performance status (PS) 0-2
• Patients must not be pregnant or breast-feeding. A negative pregnancy test is required within 7 days prior to randomization if pre- or peri-menopausal. Postmenopausal patients are defined as:
• natural menopause with last menses > 1 year ago,
• radiation induced oophorectomy with last menses > 1 year ago,
• chemotherapy induced menopause with 1 year interval since last menses, or
• serum FSH and LH and plasma estradiol levels in the postmenopausal range for the institution.
• bilateral oophorectomy

Exclusion Criteria:

• Patients cannot be on hormone replacement therapy or received prior chemotherapy for metastatic disease.
• Patients previously treated with a Tyrosine Kinase inhibitor or have evidence of an active interstitial lung disease are not eligible.
• Treatment with LH-RH analog.
• Laboratory values as follow Bilirubin >1.5 times upper limit of normal ULN, alanine amino transferase (ALT) or aspartate amino transferase (AST) >2.5 times the ULN if no demonstrable liver metastases, or >5 times the ULN in the presence of liver metastases
• Bone marrow function: WBC <1500 mm3