Testosterone, delivered by pellet implantation, has been shown to decrease breast proliferation and lower the risk of breast cancer, even in patients on conventional hormone replacement therapy. Clinical studies show that testosterone balances estrogen and is breast protective. In the past, testosterone implants have been used to treat patients with advanced breast cancer. In 1940, it was theorized that treating patients with testosterone implants earlier, at the time of diagnosis, would have an even greater benefit, preventing recurrent disease. Androgens have also been shown to enhance the effect of Tamoxifen therapy in breast cancer patients. In contrast to testosterone, Estradiol, whether delivered by pellet implant*, applied topically to the skin or taken orally has been shown to increase the risk of breast cancer. This is not surprising, as continuous Estradiol, a strong estrogen, has been shown to stimulate breast tissue in the *Million Women’s Study and in animal research studies.