The effect of hormone therapy on breast density following risk-reducing salpingo-oophorectomy in women with an increased risk for breast and ovarian cancer.

OBJECTIVE: To compare the effect of tibolone to conjugated estrogens with medroxyprogesterone-acetate (CEE + MPA) on breast density, as a predictor for breast cancer risk, in women with a high risk of breast and ovarian cancer. METHODS: Women aged 30-50 (N = 114) who had undergone risk-reducing salpingo-oophorectomy (RRSO) were randomized to tibolone or CEE + MPA. RESULTS: Breast density decreased 46% after RRSO in untreated women, 39% after treatment with tibolone, and 17% after treatment with CEE + MPA; the decrease in breast density after CEE + MPA was significantly different compared with that of untreated women (P = 0.017). CONCLUSIONS: A decline in breast density is seen after premenopausal RRSO despite the use of both CEE + MPA or tibolone, although lower breast density is seen after tibolone use.