Does tibolone reduce the risk of fracture in older postmenopausal women with osteoporosis?

This Practice Point commentary discusses a double-blind, placebo-controlled trial by Cummings et al. that investigated the effects of tibolone 1.25 mg per day in 4,534 postmenopausal women (mean age 68 years) with osteoporosis. Tibolone is a synthetic steroid with estrogenic, progestational and androgenic effects. It has been used as an alternative to estrogen to treat menopausal symptoms for 30 years. Cummings et al. found that tibolone reduced the incidence of vertebral fractures by 45%, nonvertebral fractures by 26%, breast cancer by 68% and colon cancer by 69%. The trial was discontinued 2 months before a median treatment time of 3 years because the major end point (reduction of fractures) was reached. In addition, tibolone increased the risk of stroke, although the absolute risk was small. Similarly to other compounds with estrogenic activity that increase the risk of stroke, such as estrogen and selective estrogen-receptor modulators, clinicians must weigh the risks and benefits of therapy for individual patients. This risk might be lower in women aged 50–60 years than in those aged >60 years.