An increase in mammographic density is much more common among women taking continuous combined (estrogen plus progesterone) hormonal therapy (seen in 21-43% of such women) than for those using oral low-dose estrogen (6%) or transdermal (2%) estrogen treatment. The increase in density is often apparent at the first visit after starting hormonal therapy. Due to the increased risk of breast cancer in women taking combined hormonal therapy, recommendations are that use not extend beyond 3 to 5 years [1-5].
1. Crandall CJ, Aragaki AK, Cauley JA, et al. Breast tenderness after initiation of conjugated equine estrogens and mammographic density change. Breast Cancer Res Treat 2012; 131:969-979
2. Grady D, Vittinghoff E, Lin F, et al. Effect of ultra-low-dose transdermal estradiol on breast density in postmenopausal women. Menopause 2007; 14:391-396
3. Nielsen M, Raundahl J, Pettersen PC, et al. Low-dose transdermal estradiol induces breast density and heterogeneity changes comparable to those of raloxifene. Menopause 2009; 16:785-791
4. Chlebowski RT, Anderson GL, Gass M, et al. Estrogen plus progestin and breast cancer incidence and mortality in postmenopausal women. JAMA 2010; 304:1684-1692
5. The 2017 hormone therapy position statement of The North American Menopause Society. Menopause 2018; 25:1362-1387