Objective: Evaluation of changes in mammographic and ultrasound images of the breast in women using hormonal substitution therapy (HST). Design: Retrospective clinical study. Methods: A cohort of 430 women with menopause, who have been using hormonal substitution therapy (HST) for 2-10 years, and the control population of 150 women with menopause not using HST were selected for the study. 304 women used combined HST (an oestrogen and a progestogen combination) and 126 women with surgical menopause used oestrogen hormonal substitution (EST). The mammographic and ultrasound image changes were monitored separately in the women‘ s population with combined and oestrogen hormonal substitution and also in relation to the individual types of breast and relative to the application form of the hormonal preparation. In 105 women with HST, the ultrasound image changes were monitored as well. Results: In women with menopause using HST, there was a statistically signifi cant increase of mammographic image density recorded. It was twice as frequent in the women using the combined HST as in the women using oestrogen monotherapy. In the women using oestrogen substitution, there was a monitorable mammographic density increase in a greater percentage of women with orally used preparation in comparison with the women with intradermal oestrogen administration. The mammographic density increase was more signifi cant in both groups and more frequent in women with a prevalence of fatty breast tissue (type II and III according toTabár). In ultrasound examination, in women with HST, the incidence of new and enlargement of earlier existing benign formations in the breast was recorded. These ultrasound image changes were twice as frequent in the women with oestrogen monotherapy in comparison with the women with the combined hormonal substitution. Only one woman was diagnosed with carcinoma during HST use. Conclusions: In the women using the combined as well as oestrogen hormonal substitution, a statistically signifi cant mammographic density increase was shown. The mammography density increase was statistically signifi cantly higher in women using the combined hormonal preparation in comparison with the women with oestrogen monotherapy. Enlargement or incidence was twice as frequent in women with the oestrogen monotherapy.

        Key words: hormonal substitution therapy, mammographic image density, ultrasound examination, Tabar‘s typology