Testosterone Implant Therapy in Women with and Without Breast Cancer: Rationale, Experience, Evidence

Abstract

Testosterone (T) is the most abundant biologically active hormone in women. It has a direct effect at the androgen receptor in every major organ system. Local aromatization of T is a major source of bioavailable estradiol. Adequate amounts of bioavailable T are essential for optimal health, immune function, and disease prevention. More than 80% of bioavailable T in women is from the local intracrine production of T from the adrenal precursor steroids androstenedione and dehydroepiandrosterone (sulfate). Serum T levels reflect <20% of the total androgen pool in women, which limits its usefulness in diagnosing or treating androgen deficiency. The gradual decline of androgens associated with aging is responsible for many of the adverse signs and symptoms of aging, including mental and physical deterioration. Decades of evidence support the safety and efficacy of T therapy in women. We have found that subcutaneous T implant therapy relieves symptoms of hormone deficiency in women with and without breast cancer, improves their quality of life, and maintains overall health and well-being. T does not increase and may lower the risk of breast cancer. The combination of T with an aromatase inhibitor prevents the conversion of androgens to estrogens, limiting their stimulatory effect in estrogen-sensitive diseases, including breast cancer. Adequate doses of T therapy should provide adequate levels of bioavailable T in the target organs-determined by clinical response (benefits) versus adverse side effects (risks). Pharmacological dosing of T implants in women is safe and necessary for physiological effect.