Androgens and breast

Abstract

Breast cancer (BCAA) is one of the most frequent malignancies in women in several countries, which excessive exposure to oestrogens is one of the main risk factors. The ovaries are the main source of endogenous estrogen production; however, at menopause this production sessate and extra‐gonadal synthesis, especially in ectomesenchymal cells from adipose tissue, turns the main source of estrogen production, since these cells express aromatase, an enzyme that converts androgens to estrogens. Supported by strong clinical evidence androgen replacement has been recommended for the relief of symptoms caused by female syndrome of androgen insufficiency, such as fatigue, mood swings and depression; Furthermore, experimental studies have suggested the possibility of protection of androgen replacement against BCA. In these studies, acting through their receptors, testosterone showed antiproliferative, proapoptotic and inhibited the activity of estrogen receptors and growth of mammary tumors; Clinical evidence also support the protective role of androgens in the breast. However, studies indicate that this protective role depends on the level of aromatase activity; for instance, testosterone can exert a direct inhibitory effect on tumor growth by binding to its receptor, but have an indirect effect by stimulating its conversion to oestrogens by aromatase. Obesity and insulin, as well as multiple other factors, some of which are independent risk factors for BCA, may result in overexpression of aromatase, resulting in increased localized production of estrogens, which are inducible factors of BCA. Studies on the administration of testosterone in women are scarce and controversial, and there are no studies that provide data in terms of long‐term use of safety. Thus, in this review we intend to show how androgens act in the breast. Given the current evidence, the use of androgens in women with risk factors for breast cancer is not recommended. © 2017 Sociedade Brasileira de Reprodução Humana