Tibolone and Gynecologic Cancer

Jung, Hyuk

Abstract

Tibolone is a tissue-selective compound used for the treatment of climacteric symptoms and the prevention of osteoporosis in post-menopausal women. Tibolone does not increase mammographic density. Absolute numbers of women at increased risk for breast cancer are estimated to be low or absent with both tibolone and estrogen therapy (ET), and the risk with tibolone should be significantly lower than that with estrogen/ progesterone therapy (EPT). Tibolone might therefore be preferable to EPT in certain women who have not been hysterectomised. As tibolone rarely causes endometrial proliferation, no additional progestogen is required. It also has good tolerability, being associated with a low incidence of vaginal bleeding and of breast pain. Although the best evidence currently available for the effects of tibolone on breast and endometrial cancer is from the Million Women Study (MWS), the risks reported in this observational study are probably overestimated. Recent prospective trial data show, that the absolute increase in risk for breast and endometrial cancer is lower than reported in the MWS.