Antiandrogens have only limitedly been assessed for this purpose, but the 5α-reductase inhibitors finasteride and dutasteride and the steroidal AR antagonist spironolactone have been associated with significantly reduced risk of prostate cancer.
Hyperandrogenism is associated with virilization – that is, the development of masculine secondary sexual characteristics like male-pattern facial and body hair growth (or hirsutism), voice deepening, increased muscle mass and strength, and broadening of the shoulders, among others.
Antiandrogens are used to prevent or reverse masculinization and to facilitate feminization in transgender women who are undergoing HRT and who have not undergone sex reassignment surgery or orchiectomy.
There are a few different major types of antiandrogens.
AR antagonists can be further divided into steroidal antiandrogens and nonsteroidal antiandrogens; androgen synthesis inhibitors can be further divided mostly into CYP17A1 inhibitors and 5α-reductase inhibitors; and antigonadotropins can be further divided into gonadotropin-releasing hormone analogues (Gn RH analogues), progestogens, and estrogens.
These differences are thought to be related to the fact that antigonadotropins suppress androgen levels and by extension levels of bioactive metabolites of androgens like estrogens and neurosteroids whereas selective AR antagonists similarly neutralize the effects of androgens but leave levels of androgens and hence their metabolites intact (and in fact can even increase them as a result of their progonadotropic effects).