A review of the effects of tibolone on the skeleton.

Osteoporosis is a frequent condition, which can lead to significant morbidity and even to increased mortality, owing to its complications (i.e., the fractures). Several therapies, mostly antiresorbing agents such as oestrogens, antioestrogens (chiefly raloxifene), calcitonin and bisphosphonates, are recognised for the treatment of the condition. More recently, parathyroid hormone has been added to the armamentarium of therapeutic agents. However, except for oestrogens, no other therapy alleviates climacteric symptoms. There is, therefore, some room for a therapeutic agent dealing with both osteoporosis and menopausal symptoms. Tibolone might be such an agent. However, so far, no fracture data are available; all existing studies have shown a positive action of tibolone on bone mineral density. No study has been tailored to study the antifracture efficacy. The Long Term Intervention on Fractures with Tibolone (LIFT) study has been started with the aim at filling the gap between bone mineral density maintenance and bone fracture prevention. At the same time, this study should help to understand the similarities and differences between tibolone and oestrogens as far as long-term bone action and safety are concerned, and should particularly help to clarify a possible link between tibolone use and breast cancer.