By Doctor Seibel – HouseCall®

“Is estrogen safe?” is one of the most common questions I’m asked by patients. And the answer is, “it depends.” Let me tell you why and what the new data mean to you.

Estrogen versus Estrogen and Progesterone and Uterine Cancer

Estrogen is a very potent hormone that like all medications has 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%)
  • For women in their 50s taking only estrogen, 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

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Machelle  Seibel, MD


It is a real pleasure to contribute a regular article to Families Online Magazine. Over the past 30 years I’ve had the privilege of providing care to over 10,000 women. I’ve helped them face their challenges, answered their questions, and heard the frustrations they deal with as they transition from their reproductive years to and through menopause.

As a result, my goal is to share the wisdom I’ve gained that applies directly to women’s health and menopause, or provide insights that can be of help with their families. Some articles will be on things that are ongoing health and wellness topics, and others will be comments or perspectives on important issues you notice in the news.

You will find my two most recent books helpful. They are Eat to Defeat Menopause and Save Your Life: What to do in a Medical Emergency. Click their titles now to learn more.

My websites are & There are many FREE downloads, songs, videos, eBooks and other useful content that I hope will help you stay well. My comments here aren’t intended to take the place of your healthcare provider. If you have a medical problem, be sure to ask your doctor.

If you have a topic you want me to cover, drop me a note at [email protected] and I’ll do my best to cover it for you. Receive my content-rich FREE NEWSLETTER at



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Families Online MagazineHouseCall® Medical Advice ColumnFamily Safety Tips,HealthBy Doctor Seibel - HouseCall® 'Is estrogen safe?' is one of the most common questions I'm asked by patients. And the answer is, 'it depends.' Let me tell you why and what the new data mean to you. Estrogen versus Estrogen and Progesterone...Parenting and Family Fun Activities for Kids