Effect of ultra-low-dose transdermal estradiol on breast density in postmenopausal women.

Author(s): Grady D, Vittinghoff E, Lin F, Hanes V, Ensrud K, Habel LA, Wallace R, Macer J, Cummings SR, Shepherd J

Affiliation(s): University of California Women's Health Clinical Research Center, San Francisco, CA 94115, USA.

Publication date & source: 2007-05, Menopause., 14(3 Pt 1):391-6.

Publication type: Controlled Clinical Trial; Randomized Controlled Trial; Research Support, Non-U.S. Gov't

OBJECTIVE: Women with higher mammographic breast density have increased risk for breast cancer, and there is some evidence that a change in breast density may be a marker for change in risk for breast cancer. The purpose of this study was to determine whether 2 years of treatment with ultra-low-dose transdermal estradiol results in a change in breast density. DESIGN: The Ultra-Low-dose Transdermal Estradiol Assessment was a randomized, blinded, placebo-controlled trial of 2 years of treatment with unopposed ultra-low-dose (0.014 mg/d) transdermal estradiol for prevention of osteoporosis in 417 postmenopausal women with no history of breast cancer who had not had a hysterectomy. We obtained mammograms at baseline and after 1 and 2 years of treatment from 276 of the participants. Right craniocaudal views were analyzed at a central radiology facility by a trained clinician blinded to treatment group and order of acquisition. Contour analysis was performed to define dense areas versus fatty tissue. Between-group differences in mean change in percent breast density from baseline to 1 and to 2 years of follow-up were assessed using linear regression models adjusted for clinical site. RESULTS: Participants were 66 +/- 5 years old and 94% were white. The average percent breast density at baseline was 34%. There was no significant difference between treatment groups in change in percent breast density after 1 year (between-group difference, 0.1%; 95% confidence interval, -1.3% to 1.6%) or 2 years of treatment (0.8%; -0.6% to 2.1%). CONCLUSIONS: Two years of treatment with ultra-low-dose transdermal estradiol did not increase breast density.