Baseline proliferation markers and cytopathologic findings in breast epithelium of women at increased risk for breast cancer

9694 Background: The aim of phase II chemoprevention (CP) trials is to screen potential chemopreventive agents and to identify surrogate endpoint biomarkers that can be used in large prevention studies. Tamoxifen is approved for the risk reduction of breast cancer and was shown to reduce proliferation in breast epithelium. Therefore, proliferation markers are one of the potential markers, which can be used in phase II CP studies. We are currently conducting 2 prospective clinical prevention studies evaluating changes in proliferation and apoptosis induced by celecoxib (C) or anastrazole (A) in breast tissue of high risk women. Here, we report baseline cytopathologic findings, expression of ER and Ki-67. Methods: High risk women were enrolled and underwent baseline fine needle aspiration (FNA) and started C (400 mg BID) or A (1 mg QD). ER and Ki-67 in FNA was assessed using immunohostochemistry. Immunoreactivity was scored as the percentage of positive nuclei; ≥ 10% was considered positive for ER. Ki-67% w...