Estrogen, Testosterone May Up Breast Cancer Risk

Women who take estrogen and testosterone for menopause at higher risk of breast cancer

MONDAY, July 24 (HealthDay News) -- Women who take estrogen plus testosterone to combat the symptoms of menopause are at increased risk for developing invasive breast cancer, according to new results from the Nurse's Health Study published in the July 24 issue of the Archives of Internal Medicine.

Rulla M. Tamimi, Sc.D., of Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues identified 4,610 cases of breast cancer among postmenopausal women during 24 years of follow-up, and ascertained through questionnaires their use of hormone therapies.

The researchers found that women who had gone through menopause naturally and were currently taking estrogen plus testosterone were almost 2.5 times more likely to develop breast cancer than those who had never used hormone therapy. Those taking estrogen alone had a 15 percent increased risk of breast cancer and women currently using estrogen plus progestin had a 58 percent increased risk of developing breast cancer.

While the precise reason for the increased risk is not fully understood, researchers suspect that enzymes in the breast tissue may convert testosterone to estradiol. Hormone replacement therapies may help alleviate symptoms of menopause, but "the increased risk of breast cancer may outweigh these benefits," the authors conclude.

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