Xenoestrogen
Xenoestrogens are clinically significant because they can mimic the effects of endogenous estrogen and thus have been implicated in precocious puberty and other disorders of the reproductive system.
Hormonal breast enhancement
Androgens, such as testosterone and dihydrotestosterone (DHT), powerfully suppress the action of estrogen in the breasts. At least one way that they do this is by reducing the expression of the estrogen receptor in breast tissue. In women with complete androgen insensitivity syndrome (CAIS), who are completely insensitive to androgens and have only modest levels of estrogen (50 pg/ml), the relatively low levels of estrogen are capable of mediating significant breast development, and the breast sizes of CAIS women, on average, are in fact actually larger than those of non-CAIS women. In males treated with antiandrogens, gynecomastia (enlargement of the breasts in males) and mastodynia (breast tenderness/pain) commonly occur. Antiandrogens, for instance spironolactone, are also known to cause breast enlargement and mastodynia in women. Some examples of widely used and highly-potent antiandrogens include cyproterone acetate and bicalutamide.