According to the results of a study published in the Archives of Internal Medicine, women who take estrogen plus testosterone for postmenopausal hormone therapy have an increased risk of developing breast cancer.
As women reach menopause and beyond, more than 80% will experience symptoms such as hot flashes, night sweats, sleep disturbance, and vaginal dryness. Postmenopausal hormone therapy that includes estrogen can relieve these symptoms, but the risks and benefits of hormone therapy must be carefully weighed for each woman. Previous reports suggest that the combination of estrogen plus progestin, for example, increases the risk of breast cancer, heart disease, stroke, and blood clots, but decreases the risk of colorectal cancer and bone fractures.
A small fraction of women receiving postmenopausal hormone therapy take a combination of estrogen and testosterone. Because the link between testosterone and breast cancer remains uncertain, researchers evaluated the risk of breast cancer in women taking estrogen plus testosterone for postmenopausal hormone therapy. The study followed participants in the Nurses’ Health Study over a 24-year period.
A relatively small number of the study participants reported current use of estrogen plus testosterone, although use of this combination did increase over time: In 1988, only 33 women reported current use of estrogen plus testosterone. By 1998, 550 women reported current use of estrogen plus testosterone. In 2000, roughly 2% of women receiving postmenopausal hormone therapy were taking estrogen plus testosterone.
- Among women who had experienced a natural menopause, women who were current users of estrogen plus testosterone were more than twice as likely to develop breast cancer as women who had never used postmenopausal hormone therapy.
- Risk of breast cancer was significantly higher among users of estrogen plus testosterone than among users of estrogen alone. Risk of breast cancer among users of estrogen plus testosterone was marginally higher than among users of estrogen plus progesterone.
The researchers conclude that postmenopausal hormone therapy consisting of estrogen plus testosterone increases a woman’s risk of developing breast cancer. The researchers note “Although postmenopausal therapies may provide improvement with respect to sexual functioning, general well-being, and bone health, the increased risk of breast cancer may outweigh these benefits.”
Reference: Tamimi RM, Hankinson SE, Chen WY, Rosner B, Colditz GA. Combined Estrogen and Testosterone Use and Risk of Breast Cancer in Postmenopausal Women. Archives of Internal Medicine . 2006;166:1483-1489.