Study Finds Breast Cancer Risk Increased by Long-Term Estrogen Therapy

Study Finds Breast Cancer Risk Increased by Long-Term Estrogen TherapyAfter one small study suggested that women who use an estrogen-only treatment for menopause symptoms were also at a lower risk for developing breast cancer, another, much broader study found that when such treatment is used for longer than 10 years, estrogen-only hormone replacement actually raises a woman's risk for breast cancer.

According to HealthDay, the new study was partially funded by the National Cancer Institute and the U.S. National Institutes of Health, whereas the earlier study was commissioned by drug manufacturer Wyeth. In the latest study, a team of researchers evaluated follow-up data from the Nurse's Health Study, which covered cases from 1980 through 2008. The women in the study ranged from 30 to 55 years old in 1976.

The results showed that overall, breast cancer risk was 88 percent higher in the women who received estrogen plus progesterone for 10 to 14.9 years, compared to women who did not receive the hormones. In those who used estrogen-plus-progesterone therapy for 15 to 19.9 years, the risk of breast cancer more than doubled.

Women in the study who used estrogen-only therapy postmenopause showed a 22 percent higher risk for breast cancer if the treatment was used for 10 to 14.9 years, compared to the group of women who did not. If it was used for longer than 15 years, the risk of breast cancer was 43 percent higher.

However, there was no elevated risk among women who received the treatment for less than 10 years.

According to HealthDay, Hormone replacement therapy (HRT) has dropped significantly in popularity since the U.S. Women's Health Initiative study was forced to end early in 2002, after HRT appeared to increase the risk of strokes in addition to breast and ovarian cancer. Since that time, other subtleties of HRT have emerged, which have specified risks concerning the potentially dangerous drug.

"For combination therapy there is so much data about the dangers that we really tell people that if they must take it to treat symptoms, they should only do so for a year or two at most," said study author Dr. Wendy Chen, an associate physician at Brigham and Women's Hospital.

According to the North American Menopause Society, HRT is recommended only when the lowest effective dose can be given for the shortest period.