Breast cancer chemoprevention.

Cancer chemoprevention is a new challenging issue for oncology. For breast cancer, different strategies for risk avoidance, chemopreventive measures and chemosuppressive interventions are being investigated. Attention is presently focused on two compounds, the synthetic retinoid fenretinide (4-HPR) and the antioestrogen tamoxifen, and their possible synergism. More data are now available on the expression and regulation of retinoic acid receptors in human breast cancer cells and on the consequences of the interaction of retinoids with plasma retinol binding protein. Mechanistic relationships between retinoids and growth factors like transforming growth factor-beta have been demonstrated in the frame of a central regulatory system of the state of differentiation and proliferation, in which tamoxifen is involved as well. Recent data from different trials using tamoxifen as adjuvant treatment have shown a decrease in the incidence of contralateral new primaries and that it could soon become unethical not to prescribe this drug to all node-negative oestrogen receptor-positive postmenopausal patients.