INFLUENCES OF PERCUTANEOUS ADMINISTRATION OF ESTRADIOL AND PROGESTERONE ON HUMAN BREAST EPITHELIAL-CELL CYCLE IN-VIVO

Objective: To study the effect of E(2) and P on the epithelial cell cycle of normal human breast in vivo. Design: Double-blind, randomized study. Topical application to the breast of a gel containing either a placebo, E(2), P, or a combination of E(2) and P, daily, during the 10 to 13 days preceding breast surgery. Patients: Forty premenopausal women undergoing breast surgery for the removal of a lump. Main Outcome measures. Plasma and breast tissue concentrations of E(2) and P. Epithelial cell cycle evaluated in normal breast tissue areas by counting mitoses and proliferating cell nuclear antigen immunostaining quantitative analyses. Results: Increased E(2) concentration increases the number of cycling epithelial cells. Increased P concentration significantly decreases the number of cycling epithelial cells. Conclusion: Exposure to P for 10 to 13 days reduces E(2)-induced proliferation of normal breast epithelial cells in vivo.