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Synthetic Hormones Continue to Increase Breast Cancer and Death Rates Nearly 20 Years Later

The headline on (12.20.19) states, “Remarkable New Data on Menopausal Hormone Therapy.” (1)


Folks, there is NOTHING remarkable or (much) new about the data reported. What is remarkable is that the FDA, who should be working for us, has not pulled synthetic progesterone from the market even though over three decades of data have proven that it significantly increases breast cancer risk.


But, I digress.


Let’s go back in time to 2002 when The Women’s Health Initiative (WHI), a landmark study that looked at the effect of synthetic hormone replacement therapy and outcomes such as heart attacks and breast cancer, was released. Remember, at that time, women had been told for decades that synthetic hormone replacement therapy would provide benefits without increasing the risk for breast cancer. (Keep in mind there were many previous studies that did report an increase risk in breast cancer with the use of synthetic hormones.) The WHI’s first study found synthetic progesterone in the form of medroxyprogesterone acetate (MPA) significantly increased a woman’s risk of developing breast cancer. (2)


When the 2002 WHI study was first reported it made national headlines in nearly every major newspaper. Doctors stopped prescribing synthetic hormone replacement therapy due to the results. However, most doctors failed to understand the difference between using natural, bioidentical hormones like natural progesterone, and synthetic hormones.


I had written my first book, The Miracle of Natural Hormones in 1998. In that book, I showed many studies pointing out the increase in breast cancer risk (as well as heart attacks and strokes) with the use of MPA. Natural progesterone did not have that risk. In fact, there were many studies showing a protective effect from natural progesterone.  I suggested that women should not use MPA (or any other synthetic form) and furthermore, that MPA should be pulled from the marketplace.


In 2003, after the WHI was released, I published the 3rd Edition of The Miracle of Natural Hormones. In that edition (page 21) I reviewed the WHI study in depth and I wrote, “The WHI was the latest “nail in the coffin” for synthetic hormones.” (page 195.) The WHI was a vindication for all the physicians who promote the use of natural hormones. Natural hormones are safer and more effective than their synthetic counterparts and they should be employed for all cases that require the use of hormones.”


Little did I know that 17 years later, a headline on Medscape reports remarkable new data on menopausal hormone therapy. There is no “new” data here (well, not much new). The “new” data reported in the Medscape article found that women given synthetic progesterone significantly increased their breast cancer rates decades after they discontinued the hormones. The estrogen arm of the WHI found a decreased breast cancer rate. Both findings were reported in the original 2002 study.


One of the authors of the 2019 report stated, “Women considering {synthetic progesterone} have a little more difficult dilemma because they have to be willing to accept a 20-year and maybe lifetime increased breast cancer risk…”


One reason women have to suffer with the increased breast cancer risk is because the FDA was not doing its job and removing synthetic progesterone from the marketplace. Another reason is on physicians’ shoulders for prescribing this toxic therapy in the first place. If they studied endocrinology and looked at how MPA works in the body, it is not hard to predict there will be problems with it. I describe this in more detail in my book.


The 2019 findings found that after 19 years of follow-up, women who used MPA had a 29% significant increased risk in breast cancer.   The original 2002 study found a 26% increase risk in breast cancer with MPA use. In terms of death from breast cancer, the 2019 report found a 45% increase in deaths from breast cancer in women who used MPA.


Breast cancer affects one in seven women across the US. It is a pathetic statistic. It is also pathetic to prescribe a therapy that significantly increases a woman’s risk of developing breast cancer when there are safer versions available.


Folks, I write these posts to educate you about how to make informed health care decisions. The best advice on this topic I can provide you is to avoid taking all synthetic hormones. Toxic hormones similar to MPA are found in birth control pills and IUD devices. It should be no surprise that birth control pills and IUDs have been associated with an increased breast cancer risk.


Final Thoughts: The Medscape article was infuriating. However, you don’t have to become a beast cancer statistic. Do NOT take synthetic hormones for any reason when there are natural, bioidentical hormones readily available.


More information about this topic can be found in my book, The Miracle of Natural Hormones.

To All Our Health,



Author Info

David Brownstein, M.D.

Comments ( 10 )

  • Author Icon
    Deborah Woolcott

    Greetings, Dr. B.

    I learned through some people at Dow that we are also getting inundated with estrogenics in plastics, from food packaging (metal cans are lined with it) to the PVC plumbing in our homes. Can you recommend a whole-house filtration system?

    All the best.

    • Author Icon

      I recommend Tom Lee for water filtration issues. I have no financial dealings with him. 248.557.7379 is his phone number.

  • Author Icon

    As a biochemist who has studied the distinctions in the molecular spectra of various hormones, this is not astounding or new at all, but the confusion from these combined ‘meta analysis’ continues to..increase, on not statistically relevant data.

    Here is something very important: the key is in the difference between real progesterone and synthetic analogues:

    “Synthetic progestins may also increase the conversion of weaker endogenous estrogens into more potent estrogens, thus potentially contributing to their carcinogenic effects which are not apparent with progesterone.” ( from the Holtorf paper) and these distinctions are relevant to the recent data on major depression in young women and BC pills and hormone IUDs, the Danish study and the corroborated TRAILS study are both statistically relevant and alarming.
    They ignore the data on progestins?

    Further, Dr. Lisa Mosconi who heads Alzheimers research at Well Cornell recently stated in the Atlantic interview that loss of estrogen is the major theme in her data on Alzheimer’s. Real progesterone ( and probably Te ( testosterone) help keep aggressive aspects of E2 in check. She says:””Estrogen is neuroprotective.”

    How Menopause Could Lead to Alzheimer’s – The Atlantic › archive › 2019/11 › menopause-alzheimers

  • Author Icon
    Dick Rumore

    Dr. Dave, this is my second request have been having trouble finding a holistic Dr. In the Tampa Bay area any suggestion!
    Thanks Dick

    • Author Icon

      Try looking at The International College of Integrative Medicine– I sit on the board and we have a list of docs. Also, you can ask a local compounding pharmacist—they know which docs are using natural therapies. You could also ask at a health food store.
      Good luck,

  • Author Icon

    Is there hope for women who just discover this and stop IUD – supplements or things to do to help reverse the effects ?

    • Author Icon

      The longer the synthetic items are used, the higher the risk. It is best to stop at the earliest time possible.

  • Author Icon
    Cindy Ulrich

    Now, how to get insurance to pay for natural hormones…..

    • Author Icon
      Valerie Olson

      I have had dozens of clients using the bio-identical topical progesterone cream that follows the guidelines developed by the late Dr. John Lee, who spent decades researching the hormone progesterone. It is available from and the cost is $10-15 per month, depending on your dosage need. Kajarin makes several topical creams, one that is a BiEst with progesterone (4 Balance Plus), one that is only E3 Estriol (4 Comfort) and one that is only Progesterone (4 Balance). Salivary hormone testing has validated that these are well absorbed topically, and the bio-identical hormone levels in these creams are consistent. I have been using them with my clients for over 20 years. They are more affordable than compounded creams, which may cost about $25 per month from our local compounding pharmacy.

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