Specific Aim 4: To compare the pretreatment markers of angiogenesis with post treatment markers of angiogenesis (as a secondary surrogate endpoint to breast cancer risk reduction). We hypothesize that tumor response can be measured by reduction in CD31 (microvessel count), CD105 (endoglin) and VEGF in response to hormonal therapy. There may be upregulation of TSP-1, an angiogenesis inhibitor in response to anastrozole. Angiogenic activity has been reported for ligands of the nuclear hormone receptor superfamily such as estrogens. Inhibition of the proangiogenic effects of estrogens could underlie the chemopreventive action of hormone modulators on mammary carcinogenesis. A group of investigators have indeed coined the word angioprevention as a mechanism of chemoprevention that reverses the angiogenic switch from preinvasive to invasive cancer. Additionally, it has been demonstrated that patients with various cancers whose tumor vascularity is targeted with VEGF inhibitor show higher response than patients who are treated with chemotherapy alone. Our present proposal capitalizes on the data obtained in advanced breast cancer as to the efficacy of antiangiogenesis mechanism as an option in treatment and prevention .