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Breast Cancer Risk Lower in Women on Testosterone Therapy

Reuters Health • The Doctor's Channel Newscast

NEW YORK (Reuters Health) – The incidence of breast cancer in women prescribed testosterone implant treatment for symptoms of androgen deficiency is lower than in several comparison groups, according to a prospective study.

“This hormone therapy should be further investigated for the prevention and treatment of breast cancer,” the researchers suggest in their report in Maturitas online September 10.

The authors note that testosterone therapy is being prescribed increasingly for hormone deficiency in pre- and post-menopausal women, and there is evidence that androgens are breast protective.

To investigate the impact on breast cancer risk, Dr. Rebecca L. Glaser, with Wright State University Boonshoft School of Medicine in Dayton, Ohio and Dr. Constantine Dimitrakakis, at Athens University Medical School in Greece, initiated a 10-year prospective study beginning in 2008. The current report is an interim 5-year analysis of the findings.

So far, 1388 women have been accrued to the study.  They were seen at the Millennium Wellness Center in Dayton, Ohio for a variety of symptoms of relative androgen deficiency, such as hot flashes, depressive mood, pre-menstrual syndrome, menstrual or migraine headaches, sexual problems, and bone loss. They received subcutaneous pellet implants of testosterone or testosterone combined with anastrozole designed to last 3 months.

The interim analysis includes 1268 participants who received more than one implant.  There have been 8 cases of invasive breast cancer in this group, which translates to an incidence of 142 cases per 100,000 person-years. Among women who were consistently adherent to implant therapy, the incidence equated to 73 cases per 100,000 person-years, according to the report.

The authors compare these rates of breast cancer to age-specific SEER incidence rates (293/100,000), incidence in the placebo arm of the Women’s Health Initiative (300/100,000) and in the Million Women Study (325/100,000).

Regarding side effect, Drs. Glaser and Dimitrakakis report no adverse events attributed to testosterone therapy other than expected androgenic effects, which were reversible with lowering the dose.

They conclude, “subcutaneous T (testosterone), and subsequently, T + A (testosterone + anastrozole), has a protective effect in the breast, and prevented cancer occurrence in some cases.”

Furthermore they suggest, “It is possible that continuous, subcutaneous T + A could help prevent breast cancer in high-risk women, and recurrences in breast cancer survivors.”

SOURCE: Reduced breast cancer incidence in women treated with subcutaneous testosterone, or testosterone with anastrozole
Maturitas 2013.