It seems as though we have been bombarded with estrogen stories over the past several months.

It was just a couple of weeks ago that I discussed a report from the Women's Health Initiative that estrogen-only hormone replacement therapy in post-menopausal women did not increase the risk of breast cancer.

Now there is a new report published in the Archives in Internal Medicine yesterday which has the potential to add to women’s confusion regarding the risks of estrogen therapy to treat menopausal symptoms.

The headlines may say that the study shows that estrogen increases breast cancer risk.

My interpretation is that in fact the study gives us information that rounds out our knowledge about the risks of estrogen and breast cancer, and confirms that if the drug is used as intended there is less cause for concern than was the case previously.

The study provides information on the breast cancer risk of 28,835 women in the Nurses Health Study, a long term follow-up study of nurses conducted by the Harvard Medical School and the Harvard School of Public Health.

These outstanding and highly regarded investigators have reported numerous studies on the various groups they have followed over time including nurses, doctors and other health professionals.  As a result, we have learned much about what impact various factors, such as estrogen therapy, have had on the incidence of cancer.

In this particular study they examined the breast cancer rates of post-menopausal women who had taken estrogen continually over various periods of time as compared to post-menopausal women who never took the medication.

All of the women in the study who took estrogen had had a hysterectomy. 

The women were followed from 1980 through 2002.  At the beginning of the study, there were 11,508 women participating.  Additional women who started estrogen therapy and/or had become menopausal were added every two years as further updated information was obtained.  By the end of the study, almost 29,000 were included.

A “snapshot” of the women who were in the study as of 1990 showed that almost 4500 of the participants had taken the medication for over 10 years.  3255 of the women had taken estrogen replacement for less then 5 years and 5006 women had taken estrogen for 5 to 10 years.  3288 women never took estrogen.

Some of the women had taken estrogen for 20 years or more.  If that seems strange to you, you are correct in your observation.

That change in perception about the value of long term hormonal replacement therapy has occurred over the past 4 years since the publication of the original Women’s Health Initiative study in 2002. 

We need to recall that prior to the publication of that article, there was a general consensus among physicians that hormonal replacement therapy for menopausal women not only helped them feel better, but it also had several health benefits as well.

The WHI trial demonstrated that was not the case, and a series of articles have confirmed that the consensus of experts and practicing physicians was plain incorrect.  In fact, HRT had detrimental or no effects for a number of conditions, and there were associated dangers of using the medication including an increased risk of breast cancer in women who took combined treatment with estrogen and progestin.

The results were dramatic, and the usage of the medications dropped dramatically.

As a result, the new consensus is that these medications have risks, and should be used only for symptom relief and for the shortest time possible.

Although some women may remain on HRT (including combined therapy for women who have not had a hysterectomy, since the progestin part of the regimen reduces the increased risk of uterine cancer that occurs when only estrogen is used in women whose uterus has not been removed) for a long time because they have difficulty functioning without it, the reality is they do so with an understanding that there are definite risks.

So what did the investigators find in the new Harvard study?

Basically, a post-menopausal woman on estrogen-alone treatment does not have an increased risk of developing breast cancer until she has taken the medication for more than 10 years.  Beyond that time, there is a trend of increasing risk of developing breast cancer, but the authors could not say with certainty that the risk increased until a woman had taken estrogen therapy for 20 years or more.

For women taking estrogens for 10 to 19.9 years, the authors found a “suggestion” that the risk was real, and it would be inappropriate to conclude that there was no increased risk.  But the statistics were simply not conclusive enough to say that the increased risk was real.  For these women, it would be wrong to ignore this concern, however.

To put it into other terms, for women who took estrogens for 10-14.9 years, there was an average 5% increased breast cancer risk.  For women on the medication for 15-19.9 years, there was a 19% increase in risk, and for women on estrogens 20 years or more there was an average 41% increased risk of developing breast cancer.

The other interesting observation was that thinner women taking estrogens were at greater breast cancer risk than overweight or obese women who took the hormone replacement. 

This may be because overweight and obese post-menopausal women are known to have higher blood levels of natural estrogen.  Therefore, the impact of additional estrogen from pills would have a greater net effect on the thinner women, thus increasing their risk of breast cancer.

This latter observation is interesting to me, since in a recent blog on the effects of hormonal replacement in African American women based on a report also published in the Archives of Internal Medicine had a similar finding.

So what should you do?

My first recommendation, as always, is to talk with your doctor or health care professional if you need hormone replacement therapy.  The discussion should be open and honest, and you should have a clear understanding of the potential risks and benefits that pertain to you.

You probably shouldn’t take hormone therapy if you don’t have to.  There are safer drugs, for example, to treat osteoporosis.

If you do need to take hormones, you will be prescribed a combination of estrogen and progestin if you have not had a hysterectomy, and estrogen if your uterus has been removed.

For either medication, use it only for the shortest time possible to control your symptoms.

Although there may be some benefits from hormone replacement (such as for some women a decreased risk of breast and colorectal cancer), the potential harms far outweigh those benefits.

And if you are on long term therapy with either estrogens or combination treatment, talk with your doctor whether or not you can stop them.

What we do know based on the evidence available to us is that taking hormones to improve your health is not “good medicine” based on current recommendations.  It is a symptomatic treatment, and that is the only generally accepted indication at this time.

And, although some experts believe that the data from the WHI needs to be reexamined for a variety of reasons, there is no reason today to ignore what we already know when it comes to the safest use of these medications.

Once again, if you do have to take estrogen alone for whatever reason, increased breast cancer risk is no longer a major concern for many women, but only if you are taking the estrogen for a limited period of time.

Hopefully, as these studies have accumulated, we now have a much better, consistent and scientifically sound basis for what we tell our patients about the benefits and risks of hormonal replacement therapy.