Recent advances in hormonal treatment of breast cancer

Hormonal therapy in patients with breast cancer is based on estrogen blockade of tumor cell growth. In postmenopausal patients tamoxifen still represents the hormonal agent of first choice and has shown to induce remission in patients with metastatic disease, to reduce recurrence, and to improve overall survival in the adjuvant setting. However, side effects such as slightly increased incidence of endometrial cancer have stimulated the search for other substances. Substantial progress in the development of anti-estrogens have yielded in substances with different antagonistic/agonistic profils (Toremifen, Raloxifen, Droloxifen, Idoxifen, ICI 182,780), which are currently tested in phase II and III studies. In the group of the aromatase inhibitors, which are mostly used in second-line protocols, new compounds are on the market (Formestan, Anastrazol, Letrozol, Vorozol, Fadrozol) which circumvent the main problem of inhibition of the glucocorticoid synthesis of the first-generation drugs (glutethimide) by better specificity. These already are widely used in patients with tamoxifen-resistant tumors. Whether these substances can also improve the outcome in first-line therapy is currently under clinical evaluation. An additional therapeutic intervention is the pharmacological castration (Goserelin), which orginates from the optimistic result of the surgical castration earlier days. This concept is used in premenopausal patients and currently studied alternatively and in addition to tamoxifen. In general there is hope to improve efficacy and to reduce side effects of endocrine treatment with these new compounds in the near future.