Rational approaches to the hormonal treatment of breast cancer.

Clinical observations have shown that approximately one third of breast malignancies respond to hormonal manipulation, resulting in palliation of disease and increased survival. The need to increase the benefits of such therapy and minimize morbidity has encouraged a search for a better means of patient selection. Clinical and biologic characteristics have not been sufficiently reliable in differentiating hormone-dependent and hormone-independent tumors. The presence of estrogen receptors is the best indicator of hormone dependency. The role of progesterone receptors is still under investigation, but the response rate in patients with both types of receptors appears to be increased. Therapy for the patient with an estrogen-receptor-positive tumor is a function of her menopausal status. For the premenopausal woman, oophorectomy is the treatment of choice; in the postmenopausal patient, tamoxifen is currently most frequently used. Selection of a specific therapy, however, must be based on consideration of relative efficacy and toxicity. Response rates with antiestrogens, progestational agents, and aromatase inhibitors are similar but toxicities differ. All are preferable to ablative procedures, which are irreversible and require replacement therapy for the duration of life.