Evaluation of Tamoxifen's Efficacy for ER/PR Negative,ER-beta Positive Operable Breast Cancer Patients

The current study is a multicentre, randomized,double-blind, prospective clinical trial stratified patients by the HER2 status of their cancer (negative or positive) which is sponsored by the researchers. The trial is designed to evaluate the effectiveness of tamoxifen as adjuvant therapy for ER(ER-α)/PR negative, ER-β positive operable breast cancer patients. 688 female ER(ER-α)/PR negative, ER-β(wild type ER-β1) positive operable breast cancer patients who had undergone neoadjuvant chemotherapy or directly modified radical mastectomy or breast-conserving surgery were randomly (1:1) enrolled to receive tamoxifen (20 mg per day) or placebo (2# per day) within 6 weeks after postoperative chemotherapy and/or radiation therapy if needed (according to 2013 NCCN breast cancer guideline). If the breast tumor's HER2 is positive, the patient can receive targeted therapy (Herceptin) combined with tamoxifen or placebo. The follow-up time will be eight years. The aim of this trial is to evaluate the effectiveness of tamoxifen as adjuvant therapy for ER(ER-α)/PR negative, ER-β positive operable breast cancer patients by comparing the DFS and OS between tamoxifen group and placebo group and to determine whether the percentage of positive ER-β expression is associated with the response to the hormone therapy in breast cancer.