What the JAMA Estrogen Only Study Means To You

By: Red Hot Mamas

Published: April 8, 2011

This week a study in the Journal of the American Medical Association (JAMA) sheds new light on taking estrogen. Here is what it means to you.

Estrogen versus Estrogen and Progesterone and Uterine Cancer

Like all medications, estrogen is a powerful hormone with benefits and risks that have to be weighed and personalized for each woman. Forty years ago estrogen was so popular and considered so beneficial that almost all women were encouraged to take it from the time of menopause until death. Unfortunately, it was found that estrogen alone can cause cancer of the uterus. Women who have had a hysterectomy and had their uterus removed don’t have this problem.

Then researchers discovered that women who take daily estrogen combined with progesterone for at least 10 days of the month did not get uterine cancer. There were some risks of blood clots and strokes, but overall it was believed that estrogen plus progesterone protected the uterus from uterine cancer and estrogen helped to prevent heart disease. The heart disease part of this changed with more research.

Estrogen and Progesterone and Breast Cancer/Heart Related Illness

Then in 2002, the Women’s Health Initiative (WHI) study was published in the Journal of the American Medical Association (JAMA) and suggested that women on estrogen and progesterone had an increased risk of breast cancer, stroke, blood clots and heart attacks. Women who both did and did not take estrogen and progesterone can have these problems, but those who took estrogen and progesterone had about eight more cases of these complications per 10,000 women than those women who did not take the hormones. That equals 8/10,000; 0.8/1,000; or 0.08/100 which is less than one tenth of one percent.

Still, it was statistically significant and understandably caused many women to stop taking these hormones. About the same number of those women also had a statistically significant smaller number of both broken hips and colon cancer. So estrogen and progesterone actually reduced those problems, even though there was an increased risk of breast cancer and it clearly didn’t protect against heart related diseases.

Estrogen only and Breast Cancer/Heart Related Illness


The WHI study also included another group of women who had had a hysterectomy and who did not have their uterus. Because of that, those women only needed to take estrogen; they did not have to also take progesterone. During the 6 years they were treated with estrogen, they seemed to have less risk of breast cancer, but the results were not statistically significant.

The estrogen only group of women has now been followed for 10 years after stopping their estrogen and they are the subjects of a study that was reported in JAMA in April 2011. Here’s what the study found for women who took only estrogen:

  • The risk of blood clots and stroke declined
  • The benefits of lower rates of hip fracture and colon cancer slowly wore off
  • The risk of getting breast cancer got significantly less (23% less)
  • For a woman who took estrogen in her 50s, the risk of heart attack, colon cancer, chronic disease and death was 40% to 50% lower than women who did not take estrogen.
  • For a woman who started taking estrogen only in her 70s, the risk of heart attack, colon cancer, chronic disease and death was higher than for the non-estrogen group

The Take Home Message

  • Taking estrogen alone for up to 6 years seems to be very safe for a healthy woman who begins taking it in her 50s if she doesn’t have her uterus
  • Women taking estrogen only had 40% to 50% lower heart disease problems than for women who did not take estrogen.
  • A woman in her 70s should probably not start taking estrogen at that time
  • A woman considering taking estrogen and progesterone (who still has her uterus), should talk with her healthcare provider because the decision to take or not take these hormones must be individualized to determine if it is a good choice for her

Dr. Seibel is Advisor to Red Hot Mamas and a national authority in health education. He is a Professor of Obstetrics & Gynecology at the University of Massachusetts Medical School and Director of the Complicated Menopause Program. Dr. Seibel has won national awards for research, writing, and patient education and is a sought-after speaker. Seibel is also an award-winning composer and founder of HealthRock®, teaching health literacy through music and entertainment. For more information, visit www.DoctorSeibel.com.

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