Dr. Rebecca Dunsmoor-SuFriends, I am driven to write this article because of the press release about a large study published in The Lancet, which claims to show that hormone therapy definitively increases the risk of breast cancer.

Having read the study, guidance from the North American Menopause Society, as well as thoughts from Dr. Avrum Bluming, an oncologist and author of Estrogen Matters, I wanted to share with you my concerns about taking these results at face value.

The press loves to put out “scare headlines” even if the results are more complex and muddled than that. This is another example of this type of hype. I have four serious problems with this study and its results:

One: It’s based on observational studies

This is a type of meta-analysis of multiple observational (not randomized) studies run over more than 20 years with different complex regimens. They combine both previously published and some unpublished data (which can not be verified).

For those who do not have a working knowledge of epidemiology, a meta-analysis generally involves taking previously published data and combining it to make a bigger study.

In the epidemiology world, a common joke about meta-analyses is that they represent “garbage in, garbage out.” Unfortunately, this isn’t really a joke. When you bring a bunch of flawed studies together and make the numbers bigger, you magnify their faults.

We have several large randomized trials that, with all their faults, give us better, more reliable data, which do not show an increase in breast cancer on this scale.

Two: It doesn’t reflect current practices

The regimens used in many of the studies that go into this big mash up are, in many cases, higher doses and different types of hormones than are commonly used today.

This mix of past and present practice makes it hard to draw conclusions on what doctors are prescribing today, as different hormones can behave differently in the body.

Three: The study is overly complex

The methodology used to analyze the data from these studies is exceedingly complex and hard to follow, which means it is hard to judge the results.

Dr. Bluming noted in his response to the paper, “In the editorial accompanying this paper, Joanne Katsopoulos, of the Women’s College Research Institute in Toronto, wrote: ‘The complexity of the study design makes it difficult to appraise the results and most of us will take the results on face value.’ What? Meaning: This study is such a mish-mash of complicated analyses that even we professionals can’t make heads or tails of it, and must rely on the investigator’s word of what she found?”

I have to agree with this assessment. I have a master’s degree in epidemiology, and I could not make heads or tails of the study methodology.

Four: It focuses on breast cancer to the exclusion of other concerns

This study does not take into account the balance between length of life and quality of life. Breast cancer is just one risk women face as we age, and is not even the leading cause of death.

Estrogen is one of our best and most studied treatments for osteoporosis and may well protect women from heart disease and those at risk of Alzheimer’s disease.

Most importantly, for women with significant symptoms in menopause, estrogen can be life (and sanity) saving. As always, we need to look at the whole woman when making hormone decisions, as she is more than her breasts.

Professor Michael Baum, a leading breast cancer researcher in London, released a long statement about the study. This is a portion of that response, excerpted from Dr. Bluming’s letter on the subject:

“I think the press release put out by The Lancet is irresponsible and will undoubtedly lead to a drop in the use of HRT/ERT, plunging thousands of women into a life of misery and for all we know shorten the lives of millions around the world. Remember there are more important threats to women’s lives than breast cancer, which is now only 7th in the league whilst those higher up the league might increase as a result of the withdrawal of oestrogen replacement therapy. ‘Statistical significance’ does not always translate into ‘clinical significance.’”

As much as the WHI study published in 2017 had flaws in methodology and the conclusions it made, the data from that study are still better and more reliable than the associations made in this more-recent publication.

The WHI, in the end, showed estrogen replacement alone to be protective for breast cancer (even when started late in menopause) and the estrogen and progesterone arm had a slightly higher rate of breast cancer, but not a difference that was statistically significant (which means mathematically it could be a chance or incorrect finding). It is a randomized trial that showed hormones to be overall safe for women if used correctly.

At genneve we believe every woman has a right to valid data and information when making a personal decision about whether hormones are right for her. We try to provide a balanced interpretation of complex medical studies. We also try to reach out to other experts to see what they have to say.

On balance, this latest publication in The Lancet probably does not add much to the conversation around hormones, except to stoke fear.

Rebecca Dunsmoor-Su, MD MSCE NCMP
Chief Medical Officer, genneve.com

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