A large study published in 2013 reveals a markedly reduced incidence of breast cancer in women treated with testosterone compared to women who received no hormone replacement therapy. (Glaser et al, Maturitas 2013)
1268 women were enrolled in the study, with average follow-up of five years. Treatment was provided with testosterone pellets implanted under the skin of the buttock or abdomen under local anesthesia, repeated every 3-4 months. About half of the implants contained testosterone alone, while the rest included anastrozole as well. Anastrozole blocks the conversion of testosterone into estrogen, offering added safety.
The incidence of breast cancer in the testosterone-treated group was only half that of women who did not receive hormones.
Testosterone is the most abundant sex hormone in both men and women, with blood levels in women many times higher than levels of estradiol, the primary estrogen. Testosterone is produced in both the ovaries and adrenal glands in women. Receptors for testosterone and its metabolite, dihydrotestosterone are present in many organs, including the breast.
Testosterone deficiency may occur in women prior to menopause, sometimes in their mid-thirties. Lower levels may impair libido, mental and physical health, and immune function. During menopause, supplementation with testosterone by itself ameliorates menopausal symptoms of hot flashes, night sweats, depression, reduced libido and vaginal dryness.
Several other studies have demonstrated that testosterone inhibits the growth of breast cancer cells.
In another study by the same author, 55 female breast cancer survivors were treated with testosterone pellet implants also containing anastrozole, to block conversion into estrogen. Over three years of follow-up, breast cancer did not recur in any of the patients. In two women with known metastatic disease, there was no progression.
In another report, a 90-year-old woman with breast cancer who refused all other therapy was treated with testosterone and anastrozole implants into the breast itself. Within three months, there was a 12-fold reduction in tumor size. Because of the addition of anastrozole, the estradiol level did not increase.
Menopausal women with a history of breast cancer, or who have greater risk because of overweight, family history, or dense breasts, should consider testosterone/anastrozole pellet therapy, both to handle menopausal symptoms and protect against the development of breast cancer.
Allan Sosin, MD