Pilot Study Estradiol Followed by Exemestane Hormone Receptor + Metastatic Breast Cancer

Inclusion Criteria: * Post-menopausal women with metastatic carcinoma of the breast; post-menopausal, as defined by at least one of the following: at least 12 months without spontaneous menstrual bleeding, history of bilateral salpingo-oophorectomy with or without hysterectomy, age \> 55 with hysterectomy with or without oophorectomy, serum Follicle-stimulating hormone (FSH) in post-menopausal range within 4 weeks of registration. * Positive for estrogen receptor (ER) or progesterone receptor (PgR) with positivity defined as immunohistochemical staining in \>= 10% of cells * Either measurable disease by RECIST or non-measurable evaluable disease; tests to evaluate disease (measurable and non-measurable) must be completed within 28 days prior to registration; these will include a CT scan of the chest/abdomen/pelvis and a bone scan; patients with effusions or ascites as the only sites of disease are ineligible * Performance status of 0-2 by Zubrod criteria * Patients must have a baseline CA15-3 or CA 27.29 measurement for future comparison, but any baseline value is acceptable * Patients must have had prior aromatase inhibitor (AI) therapy in the metastatic setting (any number of prior AI is allowed, this may have been any of the AI's), or have developed metastatic disease on adjuvant AI therapy; prior treatment with tamoxifen and/or fulvestrant is also allowed; patients must not have been previously treated with estradiol for metastatic breast cancer * Patients must be able t…