Medical prevention of breast cancer.

Breast cancer is the most common cancer of women in Western Europe and North America. Effective strategies of medical prevention could reduce the burden of breast cancer mortality. The best evidence for a risk reduction exists for hormonal agents such as tamoxifen and raloxifene (22-72%) or aromatase inhibitors (50-65%). However, the severity of side effects and the lack of evidence for an improved survival compromise the risk/benefit balance. In this review the results of chemoprevention studies, including new treatment approaches, are summarized with critical discussion of their use in clinical practice.