Does Estrogen Increase Risk of Breast Cancer?

Painted Lady © lynette sheppard

Painted Lady © lynette sheppard

In honor of Breast Cancer Awareness month, we bring you this informative guest post from gynecologist Bill Rawls. Estrogen sources run the gamut from oral contraceptives to HRT to surprising areas of everyday living. Women of every age should read this article with common sense advice for our health.

Does estrogen increase risk of breast cancer?
Proving that breast cancer is linked to estrogen is not difficult.  
If a woman has her ovaries removed at a very young age, and does not receive estrogen replacement, her risk of breast cancer decreases profoundly.  Of course, it’s not a very nice thing to do to someone, because risks of all other diseases, especially heart disease go up, and the body begins aging rapidly.  Even so, removing ovaries at a young age is sometimes necessary to save a life or halt a disease process.  It has occurred enough times over the years to recognize a link between estrogen (or lack of estrogen) and breast cancer…having functional ovaries that produce estrogen defines a certain risk of breast cancer.

But the baseline rate has not been stable; the past seventy-five years has seen a dramatic rise in breast cancer.  The increase has to be estrogen related, and the extra estrogen has to come from somewhere, but where?  Initially experts speculated that birth control pills might be the source.  Obvious choice – oral contraceptives contain estrogen, and if breast cancer is estrogen related, adding estrogen would increase risk, right?   Actually it doesn’t work that way.  Low dose birth control pills suppress estrogen produced by the ovaries, so the little bit of estrogen added by the pill does not raise total estrogen levels; in other words, it’s a wash.  And even though the type of estrogen in oral contraceptives is synthetic, it is metabolized similarly to natural estrogen, and therefore extra stimulation of breast tissue does not occur.  Thirty years of studying use of low dose pills has not defined any significant increased risk of breast cancer – deep breath, relax…  (Taking oral contraceptives for ten years or greater does, however, decrease risk of ovarian cancer by 50%!)

Postmenopausal estrogen replacement has also been targeted as an explanation for the rise in breast cancer...and here we might have some traction. For the past fifty years the standard for postmenopausal hormone replacement has been conjugated equine estrogens (Premarin).  Not a single estrogen, but a combination of different estrogens derived from horses, this product is very stimulating to breast tissue.  Twenty-five percent of the product’s estrogens have no look-alike in the human body and are slowly metabolized. The process of conjugation slows metabolism and increases potency even further.  When the Women’s Health Initiative, (a large study done in 2001 to evaluate postmenopausal hormone replacement) showed that conjugated equine estrogens increase risk of breast cancer, it should not have been a surprise…but use of Premarin does not explain the dramatic rise in breast cancer that has occurred in premenopausal women.

It has to be related to estrogen; and if women are not producing more estrogen and birth control pills have been proven safe, then it must be coming from the environment.  Bingo…the rise in breast cancer has directly paralleled the rise in environmental toxins; many (if not most) of which have estrogenic activity.  Virtually all pesticides have estrogenic activity and many byproducts from the plastic industry are estrogenic.  Insidiously, these chemical compounds make their way into the food supply and water supply. Even meat from the grocery store is suspect.  Hormones are readily used in the livestock industry to encourage growth.  Add to that pesticides from the corn and soybeans the animal consumes every day and finding an association between red meat consumption and increased breast cancer risk is not surprising!

And so, how do you enjoy a normal lifetime of having ovaries, live in the modern world, and still not get breast cancer?  The answer really has two parts.  The first is awareness.  Toxins with estrogen-like activity (sometimes called xenoestrogens) can enter the body by only three different routes.  They can be ingested in drinks and food, breathed in a through the lungs and absorbed through skin.  The solutions are obvious.  Eat organic whenever possible.  Lean toward fresh vegetables and fruit and cut back on meat and dairy (with the exception of fresh fish and farm eggs).  Avoid processed food.  Filter your water.  Never microwave food in a plastic container.  Keep your drinking liquids in glass containers.  Live in a place with clean air.  Be careful about things that you rub on your skin.

The second is detoxification.  Elaborate detoxification protocols are really not required; the body is designed for detoxification; it just needs a little help.  Cruciferous vegetables (cabbage, cauliflower, kale and especially broccoli) help the liver detoxify estrogen and estrogen-like compounds through a pathway that actually decreases risk of breast cancer.  Fiber from fresh vegetables and fruit helps pull toxins out of the body.  Hydration is also important, and the best hydration is from a source that most people don’t think about.  Living cells inside fresh vegetables and fruit hold a lot of water.  As the food is digested during the day, clean water is slowly and continually released; perfect for the detoxification process (compare this to the dehydrated stuff in processed food that actually requires water for digestion).

Certain supplements can enhance the detoxification process.  Milk thistle is top on the list.  This well-studied and well-tolerated herb is known to protect liver cells, increase bile flow (important for flushing the liver and getting toxins out of the body) and encourages regeneration of liver cells.  About 400-600 mg per day is enough for the average person.  Beyond milk thistle, there are scores of natural and herbal supplements that can protect liver function, improve detoxification and decrease cancer risk…anyone and everyone should take advantage of this extraordinary resource.

Awareness is essential!  Cultivate good health into your life!

Dr. Bill Rawls practices gynecology at Soundside Healthcare (Morehead City, NC) and is also the co-founder and medical director of Vital Plan (, a wellness and herbal supplement company. For more information, visit his blog at


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7 Responses to Does Estrogen Increase Risk of Breast Cancer?

  1. Kat Mortensen October 27, 2013 at 10:12 am #

    I’ll get some milk thistle! The rest, I already practice.

    Hope you are well, Lynette!

  2. LynetteSh October 27, 2013 at 10:44 am #

    Perfect – milk thistle is on my shopping list as well. Yes, thanks, I am well – hope you are too. Hugs to you!

  3. Alan Khoriaty November 25, 2013 at 1:57 am #

    Hormone therapy is not one-size fits all and we have to stop talking about it as if it is,The new research confirms that long-term hormonal therapy using estrogen and progestin may increase the risk of heart disease and breast cancer for many postmenopausal women.
    hormone replacement therapy

  4. LynetteSh December 6, 2013 at 6:43 pm #

    You are absolutely right, Alan. HRT short term use (3-5 years) shows no increase in risk but risk goes up each year after that. Of course, each woman will need to do her own risk-benefit ratio to determine what is right for her.

  5. Wendell Knight January 17, 2014 at 4:13 pm #

    Higher levels of endogenous hormones have long been hypothesized to increase breast cancer risk. Studies show that post-menopausal women with the highest levels of oestrogen and testosterone have 2-3 times the risk of women with the lowest levels. 17 In premenopausal women, the risk of breast cancer is 56% higher in those with the highest levels of serum testosterone compared with the lowest, whilst other sex hormones show no clear association, the EPIC cohort study showed. 116 Higher levels of the hormone, prolactin, have been associated with an increased risk of breast cancer, particularly oestrogen-receptor-positive tumours. 20 Having higher levels of insulin has been associated with an increased risk of post-menopausal breast cancer in women not taking hormone replacement therapy. 21 A link between high insulin levels and breast cancer might explain the 20% increased risk of breast cancer for women with diabetes shown in a meta-analysis. 87 Insulin-like growth factor 1 is positively associated with breast cancer risk. 82 .

  6. Marisa T. Macdonald January 17, 2014 at 11:28 pm #

    These probabilities are averages for the whole population. An individual woman’s breast cancer risk may be higher or lower depending on a number of known factors (see Question 3) and on factors that are not yet fully understood. To calculate an individual woman’s estimated risk, health professionals can use the Breast Cancer Risk Assessment Tool .

  7. ifat December 8, 2014 at 3:45 pm #

    As a nutritionist/Herbalist and from personal experience, I know of wonderful single herb as well as Herbal formula that work amazingly in balancing your hormones a natural way , with out the health risks

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