The Truth About Estrogen and Breast Cancer Risk
15 Oct 2015

The Truth About Estrogen and Breast Cancer Risk

Almost 15 years after sensationalized studies were published; hormone replacement therapy (HRT) is still getting a bad rap. In 2002, all hell broke loose when the Women’s Health Initiative Study was published.

This very large trial was designed to study the possible health benefits of estrogen. Women were given either estrogen alone if they’d had a hysterectomy or a combination of medroxyprogesterone (Provera®) and synthetic estrogen (Premarin®). The results showed the group who received the combination had an increased risk of breast cancer, heart attacks, strokes, and blood clots, and the trial was stopped early.

As a result, millions of women were immediately taken off HRT and left to deal with symptoms of menopause on their own. Subsequent analysis of the data showed several issues with the study and investigators ultimately determined that the “bad actor” in the whole mess was medroxyprogesterone, a synthetic progestin. The women in the study who were treated with estrogen alone showed NO increased risk of cancer (although the risk of blood clots, strokes and heart attacks was still there).

Fast-forward to today.

Confusion and fear are still rampant and many health care providers continue to assume that estrogen causes cancer – and in fact, have lumped ALL forms of hormone replacement into the cancer-causing category.

This has created huge challenges for those of us who are interested in the wellness and education of women and has caused much needless suffering for the millions of women whose quality of life is severely affected by symptoms of menopause.

It’s All About Balance

Estrogen promotes breast development in women, so of course there is a strong relationship with breast disease and the hormone that regulates breast growth – but it’s all about balance. Persistently high levels of estrogen can promote growth of abnormal cells that might otherwise have been plucked out by the immune system. This does not mean that estrogen is CAUSING cancer. But it can create an environment (which is reversible) that facilitates growth of abnormal cells if they are there.

That’s one of the reasons why having a good balance of estrogen to progesterone is so important. Progesterone has a protective effect in the setting of estrogen dominance. It counteracts the “grow, grow, grow” properties of estrogen. Women in perimenopause don’t make much progesterone because they don’t ovulate regularly, so levels are usually very low. The good news is that progesterone can be supplemented, thus helping to balance estrogen. Unfortunately, the medical community tends to lump PROGESTERONE into the category with PROGESTINS (the bad actor in the WHI Study) and this has created the fear that progesterone causes cancer.

It does not. Period.  Read more about that here.

The Bottom Line

The decision to use HRT is a very personal choice. Assessment of your breast cancer risk is the first step in making that choice. If your risk is low and your symptoms are bothersome, it should presented as an option by your physician. If it’s not, ask. Have a conversation and advocate for yourself.

AVOID oral preparations of estrogen because this delivery method contributes to the increased risk of heart attacks, blood clots and strokes. Estrogen must be metabolized in the liver and this process is what contributes to potential adverse events. Patches and creams bypass the liver and thus have much lower risk.

If you are at high risk for developing breast cancer and your quality of life is so severely impacted that your ability to function in the world is compromised, then it may be still be worth considering (unless you have a personal history of the cancers mentioned above). Ultimately, the choice is up to you and your provider.

I’d love to hear your thoughts on this. Please feel free to comment below or email me at


About Dr. Anna

Dr. Anna Garrett is a pharmacist and menopause expert who helps women who are struggling with symptoms of perimenopause and menopause find natural hormone balancing solutions so they can rock their mojo through midlife and beyond. But her clients would tell you that her real gift is helping them reclaim pieces of themselves they thought were gone forever.

Dr. Anna offers a complimentary 30-minute Get Acquainted Call to anyone who’d like to learn more about working 1-1 with her. You can schedule that at your convenience by clicking here

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Dr. Anna Garrett

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