Joy Kong, MDRegenerative Medicine Physician, Educator, and Entrepreneur

The STUDY That Gave Hormone Therapy a Bad Name ❌

20 Jun 2025 · 1 min

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1:03

Joy Kong, MD explains how the 1991 Women's Health Initiative study used synthetic hormones like Premarin and reported a 26.1% increased breast cancer risk. The absolute risk was about 1 woman per 1,000 over four years, and many participants had diabetes or high cholesterol that skewed results.

Questions this video answers

1991 (Women’s Health Initiative study)

Conjugated equine estrogen (Premarin)

Progestins (synthetic progestogens)

26.1% increased risk of breast cancer (as reported in the excerpt)

About 1 woman per 1,000 over four years (stated as ~4 women in 4,000 over four years)

Chapters

That study actually was a blow to women's health in general and every provider, every doc that was giving hormones to women. But also studies have disproven.
The earlier study. That was damning. And then they realized the replacement.
Agent were.
The culprits.
Yes. So it was a difference really, between synthetic hormone replacement therapy. So in that 1991 Women's Health Initiative study, they were using conjugated equine estrogen, which is Premarin, and they were using progestins, which are also synthetic. So what we found that not only was the synthetic product less safe, but the women had also associated comorbidities like diabetes, high cholesterol. And so what we found was a 26.1% increased risk of breast cancer in that study. But it was flawed. The true data showed one women in 1,000 over four years. So when you look at statistically, four women in 4,000 over four years, that's not statistically significant. But also because they were using unnatural.
Trauma, that's not endogenous to the human body, right?
No.
Why do you think they were using equine.
As judgment?