Mammographic breast density, hormones, and growth factors during continuous combined hormone therapy

Objective: To study the effect on mammographic breast density of two different continuous combined regimens for hormone therapy. Design: Randomized clinical study. Setting: University hospital. Patient(s): Postmenopausal women without any previous history of breast disorder. Intervention(s): The women received either estradiol valerate/dienogest or estradiol/norethisterone acetate. Mammograms and venous blood samples were obtained at baseline and after 6 months. Main Outcome Measure(s): Change in mammographic breast density. Correlations with levels of hormones, growth factors, and binding proteins. Result(s): An increase in mammographic density was recorded in approximately 50% of the women, and there were no differences between treatments. Increased density showed a positive correlation with estradiol, estrone, and sex hormone-binding globulin and showed a negative association to free T. Among hormonal factors, levels of free T were the most important for predicting increased density. Conclusion(s): Continuous combined hormone therapy with different progestogens has a marked impact on the breast.