Hormone therapy in metastatic prostate cancer

Only orchiectomy is still commonly used today either as a single therapy or in combination regimens. Hypophysectomy & adrenalectomy showed such devastating effects on the endocrine equilibrium as to be inconsistent with an acceptable quality of life or even with survival. Chemical adrenalectomy was also tried with drugs (eg. aminoglutethmide, spironolactone) leading to consequences superimposable to those of surgical adrenalectomy. Along with orchiectomy, three groups of substances are commonly used today for the hormonal therapy of prostate cancer: estrogens, LHRH agonists & anti androgens. Bilateral orchiectomy removes 90-95% of circulating testosterone. Clinical studies document 60-80% of positive responders to castration, on continued evaluation, relapse occurs usually within 6-24 months in responders, with a death rate of 50% within 6 months. The androgenic activity still remaining after castration may explain the partial & progressively decreasing effectiveness of this & other testosterone reducing therapies. Antiandrogens define substances that act directly at the target site, where interacting with steroid hormone receptors, they impede the binding of androgens. A trend towards the combination of testosterone-reducing & androgen-blocking treatment is developing in modern therapy of prostate cancer. This is due to the complementary characteristics of the two different pharmacological mechanisms that are involved. In this study castration+antiandrogen is compared to castration alone. The results demonstrate a significantly greater percentage of positive objective & subjective responses with antiandrogen than with placebo. In addition survival time was increased in patients treated with castration+antiandrogen than castration+placebo