Effects of drospirenone and norethisterone acetate combined with estradiol on mammographic density and proliferation of breast epithelial cells—A prospective randomized trial

•Menopausal hormone treatment is associated with an increased risk of breast cancer.•There are no previous data on the effects on the breast of drospirenone in combination with estradiol.•Breast density is one of the strongest independent risk factors for breast cancer.•Drospirenone in combination with estradiol increased breast density to a similar degree as standard treatment.•Breast proliferation increased slightly more by drospirenone combined with estradiol than by norethisterone and estradiol.