Postmenopausal hormone therapy with estradiol and norethisterone acetate and mammographic density: findings from a cross-sectional study among Norwegian women.
BACKGROUND: Although a number of studies have evaluated the associations between use of postmenopausal hormone therapy (HT) and mammographic density, few have assessed the effects of the medications containing estradiol (E2) plus norethisterone acetate (NETA). In particular, there are few data on the effects of the low-dose E2/NETA regimen. METHODS: We included data from 724 women, aged 50-70 years, residing in south-east Norway, who participated in a cross-sectional study conducted within the Norwegian Breast Cancer Screening Program. We assessed mammographic density using a previously validated computer-assisted method. RESULTS: After adjusting for age at screening, number of children and body mass index, women who currently used HT had 6.0% higher percent mammographic density than never-users, p