Hormone mix raises breast cancer risk

Women who try to ease the symptoms of menopause by taking a testosterone-estrogen mix raise their risk for breast cancer, according to a Harvard Medical School study.

"As women age, their natural levels of testosterone decrease, along with those of estrogen," according to Rulla Tamimi, lead researcher of the study. "Evidence suggests that a testosterone drop is associated with a poorer quality of life, including decreased sex drive and bad moods, experienced by women at this time of life."

Estrogen plus testosterone treatment may reduce these unwanted effects, increase general well-being and even lessen bone thinning. That's probably why its use has been increasing and can expect to continue increasing. Although only one federally approved pill now is available, researchers expect new formulations of the combination to be approved soon.

Because the effects on breast cancer risk of taking estrogen plus testosterone were not clear, Tamimi and her colleagues at Harvard Medical School and Brigham and Women's Hospital in Boston decided to look into risks of using the mix. Giving the treatment to a large number of women then checking their health regularly was impractical because breast cancer takes years to develop. Instead, they mined data from a study of 121,700 female nurses. Called, appropriately, the Nurses' Health Study, it collected data on use of post-menopausal hormones and other medical information of women between the ages of 30 and 55 years in 1976.

"To our knowledge, this is the first study to specifically address the risk of breast cancer for postmenopausal women in the United States who use oral estrogen plus testosterone therapy," Tamimi says. "The results show that this combination therapy poses a significantly greater risk of breast cancer compared with that of estrogen-only therapy."