Abstract
Androgens, like estrogens, can be synthesized in the breast. As both active androgens and their corresponding receptors are present in breast tissue, we conclude that they play a role in breast physiology. This is supported by the fact that insufficient androgen production or sensitivity results in the development of gynecomastia. Complete androgen insensitivity due to receptor defects leads to normal female breast development in these XY women. While breast development is completely inhibited by male testosterone levels, partial but not total degradation of a developed breast by androgen treatment appears to be possible. Breast cancer in early stages seems to fulfill the prerequisites of androgen responsiveness. Androgen treatment of advanced breast cancer has shown similar effectiveness as anti-estrogen or estrogen-ablative therapy, but also considerable side effects. It has been speculated that the use of selective androgen modulators (SARMs), either alone or preferably in addition to anti-estrogens or aromatase inhibitors, may be a promising alternative to current therapy modalities in hormone-dependent breast cancer. In addition, future studies on the use of SARMs in prophylactic settings seem to be justified.