 Treatment of breast cancer is determined by the extent of the disease. Early or localized breast cancer is treated by a combination of surgery and radiotherapy. Adjuvant systemic therapy, consisting of chemotherapy andor endocrine therapy, in tumors deemed hormone responsive, can prolong the disease-free interval and improve overall survival. However, approximately 30 to 40 of patients with early breast cancer will ultimately relapse, with either local recurrence or distant metastases, and require further systemic treatment for advanced disease. 