Does Estrogen Reduce Breast Cancer Risk?

A Hopkins Health Watch Q&A

estrogen_breast_cancer.jpgQ: It’s been all over the news that estrogen reduces the risk of breast cancer. This seems to contradict the info in What Your Doctor May Not Tell You about Breast Cancer. Please explain.

A: The only good thing I have to say about the so-called news that estrogen reduces the risk of breast cancer is that Joseph Ragaz MD and the University of British Columbia’s School of Population & Public Health did a great job getting this misleading story into the media. In truth, however, they probably had little to do with the media blitz, which has all the earmarks of drug company money and influence.

The “research” cited by Dr. Ragaz was presented at the San Antonio Breast Cancer Symposium without peer review, and with no opportunity for the public to review his statistics or methods. I’ve often said that if you tweak the data enough you can prove that the moon is made of green cheese and that pigs can fly.

The data cited for this research was taken from the controlled group of the Women’s Health Initiative (WHI), which for starters carefully selected the women in the study to exclude those with prior health problems, and to include only women who had never used HRT. The women using estrogen-only all had hysterectomies and most of them likely had non-functional ovaries. Then the data Ragaz used was tweaked even more to exclude women with a family history of breast cancer and a history of benign breast disease. Furthermore, the “estrogen” used was Premarin, which is a hormone cocktail extracted from pregnant mares’ urine, which includes many other hormones besides estrogen, including progesterone.

In the WHI observational group, women using estrogen-only had a 28% increased risk of breast cancer.

The (real) scientific evidence that estrogen promotes breast cancer is overwhelming and inarguable, and exists in research from the cellular level right up to population studies. Estrogen-only HRT also increases the risk of thromboembolic events such as stroke and blood clots, and increases the risk of ovarian cancer. Here's where you can read more about breast cancer and hormones.

While estrogen-only HRT is not advisable, that does not change the fact that estrogen, along with progesterone, can be an important addition to a hormone replacement regimen. Estrogen works wonders for hot flashes, night sweats and vaginal dryness, perks up the brain and helps aging women maintain bone density, but it should always be used with progesterone.

What’s most troubling about the claim that estrogen-only reduces the risk of breast cancer, is not that the drug companies are putting profits before women's health, which is business-as-usual, or that an individual knowlingly or naively acts as a drug company shill, but that the media so willingly and unquestioningly regurgitated this press release and thoughtlessly spread misinformation with the potential to do harm.