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

Abstract 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.