Rationale for using raloxifene to prevent both osteoporosis and breast cancer in postmenopausal women

Both osteoporosis with fracture and breast cancer are important health issues for postmenopausal women. It is well known that estrogen and estrogen receptors (ERs) play an important role in the pathogenesis of both diseases. In past decades, hormone therapy (HT), mainly estrogen plus progestin (EPT), has been frequently used for the purpose of preventing and treating postmenopausal osteoporosis because of its efficacy, but it also contributes to a significant increase in breast cancer. Currently, there is a dilemma regarding the use of estrogen for postmenopausal women. Fortunately, an increasing understanding of the action of estrogen has led ultimately to the design of new drugs that work by virtue of their interaction with the ER; these drugs have come to be known as selective estrogen receptor modulators (SERMs), and are not only effective in preventing osteoporosis and managing those with osteoporosis, but also in decreasing the incidence of breast cancer. Among these SERMs, raloxifene may be the most attractive agent based on the evidence from five recent large trials (Multiple Outcomes of Raloxifene Evaluation MORE], Continuing Outcomes Relevant to Evista CORE], Raloxifene Use for the Heart RUTH], Study of Tamoxifen and Raloxifene STAR], and Evista Versus Alendronate EVA]). The former three trials showed that raloxifene not only decreases the incidence of osteoporosis-associated fractures, but also has efficacy in breast cancer prevention. The head-to-head comparison with the anti-fracture agent alendronate (EVA trial) and the chemoprevention agent tamoxifen (STAR trial) further confirmed that raloxifene is a better choice. We concluded that since there is an absence of a therapeutic effect on relieving climacteric symptoms and there is the presence of a potential risk of thromboembolism in the use of raloxifene, this drug can be prescribed for clear indications, such as the management of osteoporosis, the prevention of fracture, and decreasing the incidence of invasive breast cancer, with careful monitoring for thromboembolism. It is reasonable to use raloxifene as an appropriate medicine that targets climacteric symptom-free postmenopausal women because of its overall favorable risk-benefit safety profile using the global index proposed by the Women's Health Initiation (WHI).