The Conjoint Actions of Androgens and Estrogens in the Induction of Proliferative Lesions in the Rat Prostate

Abstract

Despite extensive past investigations, the etiology of human prostatic carcinoma remains largely undefined. It has been suggested that age-associated changes in the sex hormone milieu may be the common cause of prostatic cancer development in man Several lines of evidence furnish support for this credence. First, circulating levels of free testosterone (T) in men decline with age while those of free 17ß-estradiol (E₂) remain unchanged, thus resulting in a much higher ratio of free E₂ to T in older men (1,2). Second, it has been reported that among black Americans who have the highest incidence of prostatic cancer in the world, both plasma free T and estrone levels are elevated at young age (3). Taken together, these findings suggest that changing levels of circulating androgens and/or estrogens or an altered ratio of the two classes of steroids in plasma are important determinants of prostatic carcinogenesis in the human male. Moreover, the influence of sex hormones could begin in the early decades of a man’s life and have a long-lasting impact on the prostate.