The Health Risks of Synthetic Hormone Replacement Therapy

Replacement Therapy

The theme of the 1950s was “better living through chemistry.” Subsequently,

a scientist named Edward Adelbert Doisy discovered various forms of estrogen. Estrogen replacement therapy began to be presented as a therapy that could allow women to free themselves from estrogen loss in order to conserve their femininity. As a result, millions of women began using the horse urine estrogen Premarin. In 1942, Premarin was approved by the Food and Drug Administration (FDA) for the treatment of menopausal hot flashes.

In reality, this novel estrogen replacement therapy was not well researched. The FDA approved these prescription drugs based on studies of a relatively small number of women. Regardless, from 1965 to 1970, estrogen replacement theory was touted as a pill that would keep women young.

Doubts About Hormone Replacement Therapy

Dr. John Lee, MD writes, “By the mid-1990s, there was ample scientific evidence that HRT was not living up to its promise and even that it was probably doing more harm than good, but many excellent studies showing this was ignored in favor of continuing hype from the drug companies about all the diseases that HRT could prevent…In the summer of 2002, two major studies published in the Journal of American Medical Association (JAMA) finally changed the fixed mindset of conventional medicine toward HRT. The first blow to HRT came from the huge Women’s Health Initiative (WHI) study, one part of which looked at the effects of the most common form of HRT, PremPro. This arm of the study was ended after five years (three years early) because of a clearly greater risk of breast cancer, heart disease, and strokes among women using PremPro [Premarin (equine estrogens) plus Prover (a synthetic progestin.)]”



The Women’s Health Initiative (WHI) was the main public randomized clinical preliminary study to follow hormonal treatment in postmenopausal ladies. The scientists found that ladies on these pills would encounter eight additional instances of intrusive breast malignant growth, seven coronary illnesses, eight strokes, and eight extra pneumonic embolisms. Shortly after the WHI study was halted, another study was released, this one from the Breast Cancer Detection Demonstration Project, part of a nationwide breast cancer screening program, and it showed that “estrogen-only hormone replacement increases the overall risk of ovarian cancer by more than threefold.”

In addition to the WHI and the Breast Cancer Detection Demonstration, studies done at Kaiser Permanente Hospital in San Francisco showed that women who were on Premarin had a rate of endometrial cancer that was five times higher than that of non-users. These findings rightfully led to HRT’s negative reputation. The Breast Cancer Detection Demonstration Project, part of a nationwide breast cancer screening program, showed estrogen-only hormone replacement therapy increased the overall risk of ovarian cancer by more than threefold.

What Does the Recent Data Show?

A study in the British Journal of Cancer states”…Combined use of estrogen and progesterone cause a significant increase in the risk of breast cancer (HR(hazard ratio))(=2.74; 95% CI, 2.05-3.65; <.001), with a 5.6% increase in HR per year of use that reached 3.27 at more than 15 years of use.

Our research shows that some previous studies are likely to have underestimated the risk of breast cancer with combined estrogen-progestogen HRT.”

Why is Hormone Replacement Therapy Still in Use?

The pharmaceutical industry has sponsored several “independent” studies claiming that estrogen is not dangerous and the results from the Women Health Initiative study were wrong and due to bad statistical techniques.

There are two main types of HRT:

  • combination HRT contains the hormones estrogen and progesterone
  • estrogen-only HRT contains only estrogen

HRT is made of synthetic hormones. This means that they are similar, but not identical to, the natural hormone they replace. In order for a medical company to patent a chemical compound, they need to alter the chemical structure of the molecule slightly, so it is different from its natural form. This is because it is not possible to patent a natural substance.

Why is HRT Linked to Breast Cancer?

●      It is less easily metabolized — which makes your liver work harder. The liver is where estrogen is metabolized.

  • The hormones in HRT are not the hormones found in the body. Foreign substances can provoke a negative response.
  • HRT is not always dosed properly. Different women have different levels of hormones and different needs.

What About Bioidentical Hormone Replacement Therapy?

Bioidentical HRT(BHRT) is a bioidentical steroid hormone that is identical in organic structure and function to human hormones. Bioidentical hormones are usually derived from a type of plant oil called diosgenin.

Overall, scientific data supports that BHRT is far safer than synthetic hormone replacement therapy. There is no study linking bio-identical progesterone with an increase in breast cancer.

Are you concerned about your hormone levels? Interested in bioidentical hormone replacement therapy? Join Moment Healthcare for comprehensive testing and consultations.


Hormone Replacement Therapy and Breast Cancer: Heterogeneous Risks by Race, Weight, and Breast Density


Hormone Replacement Therapy in Relation to Breast Cancer


The Final Word Is Out: Menopausal HRT Triples the Risk of Breast Cancer


The Haunting of Medical Journals: How Ghostwriting Sold “HRT”


  1. Bain, et al., “Use of postmenopausal hormones and risk of myocardial infarction,” Circulation 64, 42-46, 1981.

Progesterone action in endometrial cancer, endometriosis, uterine fibroids, and breast cancer by Kim et al (Kim, Kurita, & Bulun, 2013).

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