Estrogen for Triple Negative Breast Cancer

Inclusion Criteria: * histologically or cytologically confirmed breast cancer which is metastatic. * A formalin-fixed paraffin embedded tumor block (preferred) or unstained slides must be available from either a prior biopsy of the primary tumor or a metastatic site. . * Primary tumor or metastatic biopsy lacking estrogen and progesterone receptor and Her2 negative * Patients must have measurable disease. * Eastern Cooperative Oncology Group performance status 0-1. * Patients with bone metastasis at baseline must agree to treatment with intravenous bisphosphonates * Subjects may have had 0-4 lines of prior systemic chemotherapy or targeted therapy regimens administered for treatment of their metastatic breast cancer. * Age \>18 years * Life expectancy of greater than 3 months. * Patients must have adequate organ and marrow function as defined below: Exclusion Criteria: * systemic chemotherapies, targeted therapies or radiotherapy for their cancer within 2 weeks prior to entering the study * Patients receiving any other investigational agents for breast cancer treatment. * Patients with known brain metastases are excluded 3.2.4 History of allergic reactions attributed to compounds of similar chemical or biologic composition to estradiol. * Patients with any condition of the gastrointestinal tract that is expected to result in an inability to take oral medication * Dysfunctional or post-menopausal vaginal bleeding. * Uncontrolled hypercalcemia/hypocalcemia * Prior history of or active thrombophlebitis, cerebral vascular accident, myocardial infarction, deep venous thrombosis or pulmonary embolism. * History of or active hepatic adenoma. * Uncontrolled intercurrent illness * Pregnant women are excluded from this study * Patients with bone metastasis are excluded if they are unable to receive intravenous bisphosphonate therapy due to the risk for developing hypercalcemia.