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 cy cle of normal human breast in vivo. Design: Double-blind, randomized s tudy. Topical application to the breast of a gel containing either a p lacebo, E(2), P, or a combination of E(2) and P, daily, during the 10 to 13 days preceding breast surgery. Patients: Forty premenopausal wom en undergoing breast surgery for the removal of a lump. Main Outcome m easures. Plasma and breast tissue concentrations of E(2) and P. Epithe lial cell cycle evaluated in normal breast tissue areas by counting mi toses and proliferating cell nuclear antigen immunostaining quantitati ve analyses. Results: Increased E(2) concentration increases the numbe r of cycling epithelial cells. Increased P concentration significantly decreases the number of cycling epithelial cells. Conclusion: Exposur e to P for 10 to 13 days reduces E(2)-induced proliferation of normal breast epithelial cells in vivo.