Cyproterone acetate–-mechanism of action and clinical effectiveness in prostate cancer treatment

Abstract

Endocrine treatment of prostate cancer is palliative in nature. Only very rare instances of complete disappearance of prostate cancer due to endocrine management have been reported; even evidence for prolongation of life because of endocrine management is scarce. There is no randomized trial available in the literature that gives a conclusive answer to this question. The best evidence for the effectiveness of endocrine management is indirect and is derived from differences in time to progression, survival corrected for cancer death, and overall survival between treatment arms of some of the trials reported in the literat~re.'-~ As with any other type of palliative management of human disease, the issue of side effects is particularly sensitive if a cure is not an option. The effectiveness of cyproterone acetate (CPA) is well established in monotherapy in comparison to standard forms of treatment.'f4 The available informa tion has been summarized recently by Goldenberg et al.' The side effects of CPA have been studied carefully within prospective randomized and phase I1 studies and have been found to be infrequent and acceptable to patien ts. 'A The usefulness of CPA in the management of prostate cancer, especially in total androgen blockade regimens, recently has been challenged by findings in experimental systems that suggest that CPA is androgenic.',* Because of its proven effectiveness in monotherapy and because of its favorable side effect profile, CPA is used widely in many countries for the management of metastatic or locally extensive prostate