The fear around cancer and HRT is based on findings from the much flawed Women’s Health Initiative Study (WHI) that began in the 1990s. Initial data from this study suggested that taking HRT during menopause would increase a woman’s risk of not only cancer but heart disease, blood clots and stroke.
It is important to note that this is not my opinion but the findings of the WHI, which was conducted from 1991 until 2005, have been redacted.
The researchers in this study have aimed to rectify and clarify that conclusions drawn from this work were flawed, but this info is still in circulation, and many patients and providers alike don’t have the full story or aren’t abreast of current findings.
The WHI is an ongoing research project continuing to study women and aging, and they have revised their statement about HRT for menopause to read:
“Hormone therapy is an option for some women to help relieve symptoms that occur early in menopause. Further, they stated that women on estrogen replacement therapy were not more likely to die than those who are not on HRT and that the health risks of taking HRT are very low.”
But alas, initially incorrect conclusions were drawn and it is important to understand why this fear was created, what the original intentions of the WHI were, what types of hormones were used in the study, age and health of the women studied, and what more current research show us about HRT (again this study was reported on over two decades ago) so that you can make your own informed decisions about using HRT. here in the 2020s..
I liken this to asking our own parents what’s the safest sleeping practice for our own infant when we became a new mom: On their back? On their front? On their side? Our parent’s information is at least 20 years old and we want to use the current, best data to make our decisions today. But I get it as heart attacks and cancer are scary so let’s clear this up based on what we know now.
The TL/DR for this article is that there is clear benefit to bone and brain health from using HRT and specifically when bioidentical (more on that in this article) estrogen and progesterone HRT is started within 10 years of the last period there is a clear benefit to both cardiovascular health via lowering inflammation and improving insulin resistance and of course resolving hormone driven symptoms like hot flashes, insomnia, brain fog and weight gain.
What the WHI Set Out To Study – It Wasn’t Hot Flashes
The WHI was designed to study chronic disease and not specifically to look at the impact of HRT on common, hormone driven symptoms of perimenopause and menopause like hot flashes. They were not looking to study women in perimenopause or even early menopause and how HRT could help them lower risks of bone loss or dementia, stop their hot flashes, get them a good night sleep, stop fat gain or improve their quality of life.
The women in the study were older, well into menopause and they used both a combination and type of hormones not typically used today. Nevertheless, there was an increase in both breast cancer and heart disease and understandably, everyone panicked.
The Hormones Used in the WHI Are Not Common Practice in HRT Today
The WHI studied women taking synthetic estrogen and a synthetic progestin (not the same as progesterone). These are not typically used in modern HRT prescriptions for perimenopause and menopause.
The estrogen used was synthetic conjugated equine estrogens (derived from horse urine) known as Premarin. This is a very key difference.
Most HRT used now is bioidentical and not synthetic and thus is NOT the same as the estrogens derived from pregnant horse urine that the data from the WHI came from. Premarin is a combination of 21 estrogens including 18 forms of this hormone that are not made by humans.
Female humans produce 3 types of estrogen: estradiol, estriol and estrone. Most commonly HRT uses estradiol, with some compounded preparations including estriol as well (estriol is also found in popular estrogen face creams). Premarin is rarely used currently anymore but it is still available but it is not the same as the estrogen we make in our bodies or bioidentical estrogen that is used in modern HRT most often.
As well, a synthetic progestin was used in the WHI – not bioidentical progesterone. The oral progestin that was used is known as Provera or medroxyprogesterone acetate, and it is not the same as the progesterone our bodies make. While it has some similar actions, it is structurally more similar to an androgen (i.e. testosterone) than our own progesterone. It has benefits of protecting the uterus from estrogen therapy but it does not confer the sleep or calming benefits bioidentical or our own progesterone does and it has its own increased risk of breast cancer, weigth gain, acne and depression.
Thus it’s not an apples to apples comparison for the types of hormones used in the WHI compared to what is prescribed today for most women wanting HRT.
For more about the difference between bioidentical and synthetic estrogens and your options for HRT see this post.
The women in the WHI study were different from most women considering HRT today.
Part of the goal of the WHI was to study hormones and heart disease thus older women were enrolled, yet conclusions were draw across the board for women of all ages. Most women in the study were already in menopause for as long as 30 years, placing some women in the study as old as 80 and having been low estrogen for decades. We know that starting hormones after 10 years post menopause is a different ballgame than starting them early in menopause or even in perimenopause.
Heart Disease and Cancer: The Scary Stuff
Our current understanding is that HRT provides ample risk reduction for women when it comes to cardiovascular disease when treatment is started earlier. It is optimal for women to utilize HRT in their 40s and 50s or at least within 10 years of their last period to harness this benefit.
So while there was a reported increase in heart disease in the WHI women, the participants had been low estrogen for decades already and the findings were misrepresented.
Current research also suggests that using bioidentical estrogen and progesterone might actually be associated with lower breast cancer risk compared to using synthetic progestin.
While some studies do show a very low increase in breast cancer risk for women using both estrogen and progestin HRT, progestin and NOT bioidentical progesterone was used in these studies. Comparatively, when using bioidentical estrogen and bioidentical progesterone there does not appear to be a higher risk of cancer than even five glasses of wine per week. So “increased risk” sounds scary but put into perspective to other more common risk factors, it can be seen in a different light and there are studies that refute even the slight increase in cancer risk from combined, bioidentical HRT.
Lastly, studies have also shown us that receiving bioidentical HRT actually decrease risk of certain cancers, stroke, heart disease, bone loss, and diabetes.
HRT Is Not WIthout Risk
While HRT is experiencing a resurgence in popularity – and for good reason – it should be noted that it isn’t risk free, despite the vibe on Instagram.
Estrogn HRT carries a slight increased risk of blood clots but again, if started within 10 years of your last period most experts (including The Menopause Society) agree that the benefits outweigh the risks as heart disease is the leading killer of women and HRT indeed carries cardioprotective benefits. Risk of oral estrogen carries higher risk of clot than an estrogen patch or topical estrogen.
As well, many other factors such as diet, lifestyle and genetics play a role in cancer risk so your health history, family history and unique risk factors should be thoroughly assessed by your clinician to weigh your risks to benefit ratio. As well, enrolling a functional medicine doctor that specializes in womens’ health and hormones can help you even further reduce your risks and side effects.
Midlife Is More Than HRT
The HRT conversation is very imporant, but this phase of life is about so much more. I cover the things are aren’t talking enough about in this FREE Guide.
Midlife Is More Than HRT
Not seeing yourself in those happy, life has never been better midlife faces on Instagram? This guide is for you.
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References
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North American Menopause Society. (2022). The 2022 hormone therapy position statement of The North American Menopause Society. Menopause (New York, N.Y.), 29(7), 767–794. https://doi.org/10.1097/GME.0000000000002028
Margolis, K. L., Bonds, D. E., Rodabough, R. J., Tinker, L., Phillips, L. S., Allen, C., Bassford, T., Burke, G., Torrens, J., & Howard, B. V. (2004). Effect of oestrogen plus progestin on the incidence of diabetes in postmenopausal women: results from the Women’s Health Initiative Hormone Trial. Diabetologia, 47(7), 1175–1187. https://doi.org/10.1007/s00125-004-1448-x
https://www.nhlbi.nih.gov/science/womens-health-initiative-whi
https://www.womenshealth.gov/30-achievements/25
Writing Group for the Women’s Health Initiative Investigators. (2002). Risks and Benefits of Estrogen Plus Progestin in Healthy Postmenopausal Women: Principal Results From the Women’s Health Initiative Randomized Controlled Trial. JAMA: The Journal of the American Medical Association, 288(3), 321–333. https://doi.org/10.1001/jama.288.3.321
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https://pubmed.ncbi.nlm.nih.gov/16682578/
Stute, P., Wildt, L., & Neulen, J. (2018). The impact of micronized progesterone on breast cancer risk: a systematic review. Climacteric, 21(2), 111–122. https://doi.org/10.1080/13697137.2017.1421925
van Seumeren, I. (2000). Weight gain and hormone replacement therapy: are women’s fears justified? Maturitas, 34, S3–S8. https://doi.org/10.1016/s0378-5122(99)00073-0
https://breast-cancer-research.biomedcentral.com/articles/10.1186/bcr1792
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Cagnacci, A., & Venier, M. (2019). The Controversial History of Hormone Replacement Therapy. Medicina, 55(9). https://doi.org/10.3390/medicina55090602
Stevenson, J. C. (2009). HRT and cardiovascular disease. Best Practice & Research Clinical Obstetrics & Gynaecology, 23(1), 109–120. https://doi.org/10.1016/j.bpobgyn.2008.10.010
Stute, P., Wildt, L., & Neulen, J. (2018). The impact of micronized progesterone on breast cancer risk: a systematic review. Climacteric, 21(2), 111–122. https://doi.org/10.1080/13697137.2017.1421925
van Seumeren, I. (2000). Weight gain and hormone replacement therapy: are women’s fears justified? Maturitas, 34, S3–S8. https://doi.org/10.1016/s0378-5122(99)00073-0