Menopause hormone therapy (MHT): what recent studies really say

Few subjects in women's health have been as badly understood as menopause hormone therapy (MHT). For twenty years, a single sentence was enough to discourage millions of women: "hormones give you cancer and block your arteries". That fear is very real, and it is legitimate, but it rests largely on a partial reading of a 2002 study. Since then, science has considerably refined its understanding. The aim of this article is neither to push you towards MHT nor to steer you away from it: it is to give you the facts, with their nuances, so that you can discuss them calmly with your doctor.

2002: the shock that stopped everything

In July 2002, one arm of the large American Women's Health Initiative (WHI) study, which was testing combined estrogen + progestogen therapy against placebo, was stopped early. The researchers had observed an increase in the risk of breast cancer, stroke and clots^[1]. The news travelled around the world. Within a few months, MHT prescriptions collapsed, and a generation of women gave up hormones out of fear.

The message people took away, "MHT is dangerous", was not exactly what the study showed, however. And it is that detail, long overlooked, that changed things.

What the WHI really showed (and why it was misinterpreted)

The crucial point is the age of the participants. The women included in the WHI were 63 years old on average, and many were more than 10 years past their menopause when they started treatment^[1]. Now, that is not the typical profile of a woman starting MHT today: she is more likely to be between 50 and 55, in early menopause, and seeking relief from symptoms.

The absolute risks, moreover, were modest. And above all, later analyses added nuance to the picture. The long-term follow-up of the WHI, published in 2017 and covering 18 years, found no increase in overall mortality, nor in cardiovascular or cancer mortality, in women who had received MHT for 5 to 7 years^[2]. In other words: the concern of 2002 did not translate into excess deaths over the long term. The initial message, by focusing on relative risks without distinguishing between ages, had given a more alarming picture than the reality for the majority of the women concerned.

The "window of opportunity": a question of timing

From this rereading came a central idea, the timing hypothesis (the "window of opportunity"). According to it, the effects of MHT on the heart and blood vessels depend on when it is started relative to menopause^[4].

The ELITE trial, published in 2016, was designed specifically to test this idea. It showed that oral estradiol slowed the progression of atherosclerosis (the thickening of the arteries) when it was started less than 6 years after menopause, but not when it was started 10 years or more afterwards^[5]. So the same treatment could be rather protective in a younger woman in early menopause, and of no benefit, or even risky, in an older woman.

That is why current guidelines are built around a simple threshold: the benefit-risk balance is most favorable in women under 60 or less than 10 years from their menopause, with no contraindication^[3].

The established benefits

MHT is not only "less risky than people thought": it brings real, well-documented benefits.

• Hot flashes and night sweats. MHT remains the most effective treatment for vasomotor symptoms, which is its main recognized indication^[3].
• Bone strength. In the WHI, combined therapy reduced the risk of fractures, including hip fractures, with an improvement in bone density^[7]. MHT is thus recognized for the prevention of bone loss^[3].
• Quality of life. By improving sleep, mood and intimate comfort, relieving symptoms can have an appreciable overall effect: a benefit that each woman assesses according to her own experience.

The real risks, and for whom

Adding nuance does not mean playing things down. MHT carries real risks, which have to be weighed against the benefits, and which depend a great deal on the type of treatment and on the woman's profile.

Breast cancer. This is where the nuance matters most, because not all MHT is the same. An analysis of the two WHI trials showed opposite effects depending on the formulation: estrogen combined with a progestogen was linked to an increase in the risk of breast cancer, while estrogen alone (prescribed to women without a uterus) was associated with a decrease in that risk^[6]. This distinction between estrogen alone and combined estrogen is essential to understanding the data. It does not, however, mean that estrogen alone protects against breast cancer: that result comes from an American trial conducted with conjugated equine estrogens, and it is not found everywhere. The HAS, for its part, classifies breast cancer among the risks of MHT, a risk that increases with the duration of treatment.

A French clarification that changes the reading. The WHI tested conjugated equine estrogens combined with medroxyprogesterone acetate. That is no longer the regimen prescribed in France. The French reference regimen combines estradiol, most often by the transdermal route, with natural (micronized) progesterone or with dydrogesterone. The GEMVi patient information sheet (2025) states that with this combination, French and European studies have not found an increase in the risk of breast cancer over five to six years, whereas an Anglo-Saxon type of MHT is associated with about 6 additional cases per 1,000 women after ten years of use. This is not a certificate of harmlessness: it is one more reason to ask your doctor which hormones exactly he or she is offering you.

The heart and clots. In women who start MHT late (more than 10 years after menopause or after 60), the benefit-risk ratio becomes less favorable, because of higher risks of coronary heart disease, stroke and clots^[3]. This is exactly the reverse of the window of opportunity: the time factor then works against the treatment.

These risks do not apply in the same way to everyone. A personal or family history of breast cancer, of thrombosis, of stroke, smoking, high blood pressure: all of these weigh in the assessment, and only a doctor can factor them into your situation.

The situations in which MHT is not possible, and the safeguards

Articles for the general public often move too quickly over this point. There are situations in which MHT is not offered. The GEMVi cites a history of breast cancer as a contraindication. The Menopause Society adds cancer of the uterus, unexplained uterine bleeding, liver disease, a history of clots and established cardiovascular disease. This list is not a questionnaire to be filled in alone: it indicates what must be said at a consultation, including what you believe to be trivial.

With a uterus, estrogen is never taken on its own. It must be combined with a progestogen, for at least twelve days a month, to protect the lining of the uterus and reduce the risk of endometrial cancer. This is a non-negotiable point of the French guidelines. Estrogen alone is reserved for women whose uterus has been removed.

A treatment that gets reassessed. The HAS calls for prescribing at the minimum effective dose, for a limited duration, and for reassessing the benefit-risk ratio at least once a year. The GEMVi sets no theoretical maximum duration, but recommends the same annual reassessment, particularly beyond five years. Usual follow-up includes an annual clinical examination with weight and blood pressure, and taking part in organized breast cancer screening by mammography every two years between the ages of 50 and 74.

To put actual practice in France in context: the ANSM reports that in 2024 the transdermal route accounted for 87% of estrogen prescriptions, and that the combination of estradiol with micronized progesterone or with dydrogesterone concerned about 75% of women treated between the ages of 45 and 60.

The route of administration changes things

One and the same hormone does not have the same effects depending on whether it is swallowed or applied to the skin. The oral route (tablets) passes through the liver, which influences coagulation. The transdermal route (patch or gel) avoids this first liver pass.

A large British study published in 2019, based on general practice databases, compared the two routes: oral preparations were associated with an increase in the risk of venous thrombosis, whereas transdermal preparations were not, a result that held whatever the dose^[8]. For women with risk factors for clots, the transdermal route is therefore often preferred. It is a concrete example of how a technical choice can change the safety profile of a treatment.

MHT is an individual decision, with your doctor

If you were to remember only one thing, it would be this: there is no universal answer. MHT is neither a poison nor a fountain of youth. It is a medical treatment whose benefit-risk balance depends on your age, on how long it has been since your menopause, on the intensity of your symptoms, on your history, on the type of hormones and on their route of administration.

Two women of the same age can reach opposite conclusions, and both be right. That is why the learned societies insist on an individualized approach: the right treatment, at the right dose, in the right woman, at the right time^[3]. That decision is made at a consultation, after a conversation about your expectations and an assessment of your personal risks, not from a newspaper headline, nor even from an article like this one.

In summary

The fear inherited from 2002 long deprived women of a treatment that could have relieved them, on the basis of an overly broad interpretation of a study conducted in a particular profile. Recent data paint a finer picture: MHT remains risky in certain situations, but it offers concrete benefits for other women, particularly when it is started early, with the right formulation and the right route. Neither for nor against: MHT deserves a calm and personalized discussion. The best starting point remains understanding where you are in your menopause, then talking about it with a health professional.

⚠️ This article is provided for informational and educational purposes only. It does not replace medical advice, diagnosis or treatment. Always consult your doctor or a qualified health professional with any questions about your health.

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