Mammographic changes in postmenopausal women on hormonal replacement therapy.

The purpose of this study was to investigate the extent of the effects of hormonal replacement therapy (HRT) on the mammographic breast pattern in postmenopausal women. In a hospital-based study mammographic examinations of 81 postmenopausal women were evaluated retrospectively, before and after 1-2 years of treatment with oestrogens or a combination of oestrogens and progestagens. Each individual mammographic film was examined separately, and the glandular tissue was classified according to a modified Wolfe classification. In a screening-centre-based study two consecutive mammograms, with a 2-year interval, of 645 women, of whom 70 were using some kind of hormone therapy, were evaluated retrospectively. In the hospital-based study 31 % of patients treated with combination HRT showed an increase in fibroglandular tissue compared with only 8.7 % in the group treated with oestrogens alone. The difference was statistically significant (p = 0.046). In the screening-based study 14.3 % of the women using hormonal therapy showed an increase, whereas in the non-users no increase was found (p = 1.24 x 10(-10)). After beginning HRT many women (between 14 and 25 % in our experience) can be expected to undergo a mammographically detectable increase in fibroglandular tissue. Radiologists should be aware of the aetiology of such changes, and can obtain information on HRT most conveniently by having the technologist routinely question each patient.