RESUMO
Breast cancer is the most common cancer of women worldwide. Its frequency increases throughout the female lifespan. Epidemiological research has clearly identified important reproductive risk factors for breast cancer, including age at menarche, age at menopause, age at first-term pregnancy and nulliparity, which provide important clues to the hormonal origin of this disease. The widespread use of exogenous sex steroids as contraceptive agents and as hormonal replacement therapy has been a source of concern and generates discussion about their effects on breast health. Lifestyle changes, exercise or diet could play a role in primary prevention of breast cancer. Regular exercise, ingestion of adequate amounts of fruit and vegetables, limiting alcohol consumption, avoidance of obesity in post-menopausal women, and perhaps the use of olive oil, may all have a protective effect and should be considered by women. There is insufficient scientific evidence of the role played by phyto-oestrogens on breast cancer risk. Other preventive measures that include the use of drugs such as statins or aspirin should not be recommended until we have more information about their effects on the breast. Especially for high-risk women, all the aforementioned measures may be not enough, and chemo-prevention should be considered. The use of selective oestrogen receptor modulators (SERMs) to reduce breast cancer risk is still being evaluated. Tamoxifen was the first SERM approved for the reduction of breast cancer incidence in women at high risk. However its use has limitations, due to significant side effects. Raloxifene has been approved for the prevention and treatment of post-menopausal osteoporosis and has provided excellent indications of breast cancer risk reduction, with a more favourable profile than tamoxifen.
