[Synthetic steroid anti-hormones]

Steroid antagonists are competitive inhibitors of the corresponding hormone for binding to its specific receptor. Their antagonist action depends on their metabolism and on partial antagonist action depends on their metabolism and on partial agonist effect which is variable with the species, the tissue or regulated gene. Their action in tumoral proliferation is exerted via autocrine, paracrine or endocrine pathways. In addition they may have their own effect mediated by the corresponding steroid receptor (ex: antiestrogen, antiprogestin...) or by specific binding sites (ex: tamoxifen binding sites). They are prescribed in the treatment of hormone dependent cancers. Some sex-steroid antagonists are largely used in adjuvant therapy because of their good clinical tolerance. Study of their interest as a chemopreventive agent in cancer is actually in progress. Pure antihormones could be highly interesting in advanced cancers but they might have secondary effects in long term therapy. In spite of available steroid antagonists have widely proven to be valuable tools in the treatment of breast cancer, the ideal anti-steroid compound should be pure antagonist in the considered target tissue and partial antagonist in the others.