Maintenance Hormone Therapy for Postmenopausal HR Positive Advanced Breast Cancer

This is a prospective, single arm phase II study to evaluate the efficacy and safety of fulvestrant as a maintenance hormone therapy after first-line chemotherapy for postmenopausal HR positive advanced breast cancer. Approximately 58 women who have stable disease or responded to first line chemotherapy with at least 4 and less than 8 weeks of treatment for metastatic breast cancer will be enrolled to this study and receive fulvestrant 500mg as a maintenance therapy. The treatment will continue until the objective disease progression or intolerable AE. Efficacy will be determined based on tumor assessments performed by each investigator according to RECIST (Response Evaluation Criteria in Solid Tumors ) 1.1. Safety will be monitored based on the frequency and severity of adverse events (AEs), as assessed by Common Terminology Criteria (CTC) grade version 4.0. Tumor assessments will be assessed by computed tomography (CT) or magnetic resonance imaging (MRI) every 12 weeks for all patients until documented evidence of objective disease progression. Reporting of SAEs (serious adverse events) to regulatory authorities will be done by the investigator in accordance with local regulations.