Perspectives for the hormonal therapy of breast cancer

The role of estrogens, including its sources, tissue distribution, metabolism, and mechanism of action, is discussed in this review. The ER alpha and beta are functioning separately, and there is a physiological balance between their activity. Whenever this balance is over thrown due to endogenous or exogenous carcinogenic factors, malignancy develops. Risk factors of breast cancer are listed and evaluated individually. It should be stressed however, that their carcinogenic effect sums up. The knowledge of established risk factors rises the possibility of chemoprevention, which might be highly desirable in case of gene carriers. Special emphasis is attached to the SERM molecules which act as antiestrogens. Their antitumour effect is largely used in the treatment of hormone sensitive advanced breast cancer patients, and their efficacy has been proved in adjuvant therapy as well. Their preventive use might also be justified, especially in gene carriers. Aromatase inhibitors form a special class among the SERM molecules. In Hungary, anastrozole, letrozole and exemestane are widely applied for the therapy of breast cancer patients, while raloxifene has only been introduced recently, mainly in order to prevent osteoporosis. The therapeutic value of fulvestrant is unknown yet and its antitumour effect has to be explored. The therapeutic significance of these molecules lies in the fact that they might be effective after the development of tamoxifen resistance. There are several explanations for this phenomenon offering new targets for the further development of a succesful antitumour chemotherapy.