. . . according to the findings of the Ultra-Low-dose Transdermal Estradiol Assessment, a randomized, blinded, placebo-controlled, 2-year trial involving about 400 postmenopausal women.  

The authors of the study gave the women, who had no history of breast cancer or hysterectomy, either unopposed 0.014 mg/d transdermal estradiol or an identical placebo patch.  

The finding of no significant difference between treatment groups in change in percent breast density after 1 year (between-group difference, 0.1%; 95% CI, –1.3%–1.6%) or 2 years of treatment (0.8%; –0.6%–2.1%) is significant because women with high breast density are at already increased risk for breast cancer. And interventions like combination estrogen/medroxy-progesterone that further increase breast density can put women at unacceptable risk. The ultra-low-dose transdermal estradiol also improved bone density and had no negative effects on the uterus.  

. . . according to the findings of the Ultra-Low-dose Transdermal Estradiol Assessment, a randomized, blinded, placebo-controlled, 2-year trial involving about 400 postmenopausal women.