[Hormone therapy--recent advances]

Inhibitory effects of hormone therapy on the growth of cancer can be found only in cancers whose growth is stimulated by hormones. Among the various kinds of steroid-or peptide-dependent (or responsive) tumors, estrogen-dependent breast and endometrial cancers and androgen-dependent prostate cancer have been shown to have high incidences. Therefore, the suppression or disappearance of the production or action of estrogens or androgens has been used as a common form of hormone therapy. Although surgical therapies such as removal of the ovaries, adrenals, hypophysis or testes have been used as the major hormone therapies, medicinal therapies such as the administration of antiestrogen, aminoglutethimide, medroxyprogesterone acetate, antiandrogen and/or high doses of LHRH have recently become the major types of hormone therapy. Fortunately, hormone therapy produces very few side effects compared with various other therapies for cancer. However, hormone therapy has been shown to be effective only in 30% of breast cancers or endometrial cancers, and 70% of prostate cancers. Furthermore, loss of hormone dependency generally occurs during hormone therapy. Therefore, useful methods for the growth inhibition of hormone-independent recurrent tumors should be developed. Various kinds of chemotherapies combined with hormone therapies have recently been used. Although these chemoendocrine therapies have resulted in an increase in response rate, overall survival has not been significantly improved in comparison with endocrine therapy alone. Since recent findings have shown that the growth of sex steroid-dependent cancer is mediated by sex steroid-induced growth factor (s) secreted by the cancer cells(autocrine control), suppression of the production or action of such growth factor (s) should be investigated as a future form of endocrine therapy; a loss of hormone dependency might occur through the production of such growth factor (s) without hormone stimulation.