Hormone balance is key to breast health, as well as overall health. Both established and evolving breast cancer research points to the roles of estrogen, progesterone, testosterone, DHEA, cortisol, and thyroid and Vitamin D as key players in breast cancer prevention.
Quick links to information on this page:
- The Estrogen/Progesterone Balance
- Testosterone and DHEA
- Vitamin D
The hormone that is fundamental to the female of the species is actually a family of three: estradiol, the most active form of estrogen; estrone, the inactive storage form of estrogen; and estriol, the weaker of the estrogens.
Estrogen has been labeled “the angel of life,” because it makes cells grow, developing the uterus, breasts, periods, pregnancy and the egg within the ovary—and “the angel of death,” because in excess it becomes toxic to the body. As they say, too much of a good thing can be dangerous, and too much of an estrogen that causes cells to multiply out of control is a recipe for breast cancer. Determining symptoms of estrogen dominance is a smart move since an imbalance of high estrogen to low progesterone that goes undetected for too long is not a risk worth taking.
Estriol, the weakest of the three estrogens is thought to protect against breast cancer by softening the effects of its more potent sisters. A revisiting of the literature finds that estriol is vitally important, precisely because it is a weak estrogen. And a number of studies, published over four decades, have demonstrated that estriol’s unique and perhaps most important role, may be to oppose the growth of cancers, including breast cancer. When lower-strength estriol is used topically, it does not raise the risk of breast cancer as stronger and/or synthetic estrogens do.
Estriol’s protective action is linked to its ability to bind loosely to hormone receptors on the cell walls of breast tissue, thus blocking more potent estrogens from occupying the sites and stimulating breast cells to grow. Unlike these more excitatory estrogens, estriol does not stimulate growth nearly as much. Some of the best research on the inherent strengths of this weakest of estrogens has been done in Europe where estriol has been more readily available and studied for years:
- In a 2006 study of nearly 8000 Finnish women over the age of 50 who took estriol for as little as 6 months to over 5 years, oral use of estriol did not increase the risk of breast cancer.
- The Fournier study in 2005 investigating cancer risk factors in 98,997 French women born between 1925–1950, observed no significant increase in breast cancer risk among users of weak estrogens, such as oral estriol or low-dose estrogens delivered vaginally.
- A 2003 study that looked at topical vaginal estrogen therapy in women previously treated for breast cancer concluded that estriol was safe for use in post-menopausal women previously treated for breast cancer.
- Adding further to the evidence for estriol’s breast protective powers, was a study in 2000 that looked at mammographic density in post-menopausal women treated with tibolone, estriol or conventional hormone replacement therapy. The researchers found that estriol does not increase breast density.
- A landmark study in 1989 conducted by Swedish researchers looked at breast cancer risks in over 23,000 users of hormone replacement therapy. Published in the prestigious New England Journal of Medicine, the investigators found that use of estriol did not increase breast cancer risks, and further that long-term use of unopposed estradiol—that is, unbalanced by progesterone—increased the risk of breast cancer, and that this risk might even be increased by the addition of synthetic progestins.
- In a follow-up study in 2003 the researchers concluded that indeed, continued use of HRT containing progestins rendered the highest risks for breast carcinoma.
Dating back to the 1960s, the evidence has strongly suggested that estriol may protect against breast cancer. At that time, Henry Lemon, MD, head of the division of gynecologic oncology at the University of Nebraska College of Medicine, hypothesized that women who develop breast cancer have too little estriol relative to the more potent estrogens (estradiol and estrone) circulating in their bodies and that women with breast cancer generally had the lowest levels of estriol. He decided to test his hypotheses by treating women who already had breast cancer with estriol. In a clinical trial of 29 women in peri- or postmenopause with breast cancer, treatment with estriol either caused the cancers to go into remission or arrested tumor growth in 37 percent (6) of his patients. Estriol treatment also appeared to have almost no side effects. Dr. Lemon subsequently devoted his medical career to researching the benefits of estriol as a safe hormone replacement and as a breast cancer preventative.
Women in Balance suggests talking to your physician about bioidentical hormone treatments containing estriol.
Progesterone is the sister hormone to estrogen, working in tandem with it to regulate and protect the health of the reproductive system throughout our fertile years. Among its many vital functions, progesterone governs the second half of the menstrual cycle and is essential to maintaining a pregnancy to term. It also plays a part in the regulation of blood sugar levels, has inherent calming properties, and protects breast, brain and bone health. When it comes to breast cancer prevention, progesterone’s most important role in the body is to balance estrogen.
Like its teammate, estrogen, progesterone is primarily made in the ovaries but unlike estrogen it can only be produced at ovulation. The ruptured follicle that releases an egg upon ovulation then pumps out progesterone for the rest of the cycle. So if and when we don’t ovulate, our bodies do not produce enough progesterone to keep estrogen levels in check—and that sets us up for estrogen dominance. In a nutshell: progesterone deficiency = estrogen dominance = heightened risk for breast cancer.
Lack of ovulation, whether it occurs naturally as the result of aging ovaries, or unnaturally, from extremes of stress, exercise, diet, and/or use of synthetic hormones in HRT or birth control pills, will cause estrogen to drop from 40 to 60 percent (enough to stop the menstrual cycle), but progesterone levels plummet much lower, to nearly zero in some women. It all boils down to the right ratios: in the landmark British study (Mohr, PE; Br J Cancer 1996) researchers found that women with breast cancer whose progesterone level at the time of surgery was above the adequate level, had significantly improved chances of survival.
Estrogen and progesterone are finely balanced and are said to “oppose” one another by performing opposite functions, but in so doing, they balance or mediate each other. The following lists clarify the counterbalancing effects of progesterone upon excess estrogens:
Excess Estrogen Effects
- Creates quickly-multiplying cells in the lining of the uterus
- Causes breast stimulation
- Increases body fat
- Depression and headaches
- Salt and fluid retention
- Interferes with thyroid function
- Increases blood clotting
- Decreases sex drive
- Impairs blood sugar control
- Loss of zinc and retention of copper
- Reduces oxygen levels in all cells
- Increases risk of endometrial cancer
- Increases risk of breast cancer
- Slightly restrains osteoclast function
- Reduces strength of blood vessels
- Increases risk of gallbladder disease
Balancing Progesterone Effects
- Maintains a nourishing uterine lining
- Protects against fibrocystic breasts
- Helps use fat for energy
- Natural anti-depressant
- Natural diuretic
- Facilitates thyroid hormone action
- Normalizes blood clotting
- Restores sex drive
- Normalizes blood sugar levels
- Normalizes zinc and copper levels
- Restores proper oxygen levels
- Helps prevent endometrial cancer
- Helps prevent breast cancer
- Stimulates osteoblast bone building
- Restores strength of blood vessels
—From What Your Doctor May Not Tell You About Menopause.
As the above lists clearly illustrate, estrogen and progesterone are fundamental balancing partners at every stage of a woman’s lifecycle. At midlife, supplementing a balanced cocktail of both, relieves symptoms and protects against breast cancer. Remember that without progesterone, estrogen can become toxic to the body as a potent promoter of breast cancer.
Testosterone is an androgenic hormone, or “androgen” (from the Greek, andro for “male”), so named because it is most commonly associated with the development of male characteristics. Although testosterone is present in much smaller amounts in women than in men, it has a wide range of essential functions for a woman’s health. These include maintaining libido and sexual function, as well as the normal growth and renewal of muscles, bone and other tissues. It may also have a role to play in protecting breast health at a cellular level.
Levels of testosterone and its precursor, DHEA, decrease in women at menopause, and are often particularly low in women who have a “surgical menopause” (removal of the ovaries). This is when symptoms of “androgen deficiency” can start to become apparent. Along with the most noticeable effect of lowering libido, low testosterone and DHEA can also result in decreased bone and muscle mass, depression, and vaginal dryness.
Sometimes, however, mid-life women can develop “androgen dominance” as testosterone levels can become relatively high while ovarian estrogen and progesterone production declines. Drs. John Lee and David Zava, in their book What Your Doctor May Not Tell You About Breast Cancer speculate that elevated levels of testosterone in women may be the result of the hormonal imbalance caused by menopausal estrogen dominance and the lack of progesterone.
In healthy individuals, normal levels of cortisol—the adrenal hormone that maintains the immune system and manages our stress-coping response 24 hours a day—should be highest in the morning when we need to “get up and get going,” and decrease steadily to its lowest point at night, when we need to sleep. But the stress-coping demands of 21st century living can wreak havoc on this normal circadian rhythm, disrupting our ability to sleep through the night, focus on our work, and take life’s daily challenges in stride. When cortisol levels are out of balance, we tend to feel “tired and wired” all the time and/or may suffer from asthma and allergies, chemical and noise sensitivities, anxiety, and eating disorders. We may find ourselves crashing in the afternoon, craving sugar and caffeine to cope, and catching every cold and flu bug that comes along. The bottom line is adrenal exhaustion: when the body can no longer keep up with the demand for constant cortisol we hit bottom and may find ourselves at serious risk for chronic illness and autoimmune disease, premature aging, and a breast cancer just waiting to happen.
The Colorado Thyroid Disease Prevalence Study in 2000 found the rate of hypothyroidism in the general population to be approximately 10%, with an estimated 13 million undiagnosed cases of low thyroid among American adults. Interestingly, women have an approximately seven times greater risk for developing thyroid problems than do men. Thyroid hormone regulates metabolic rate, so low levels tend to cause unwanted weight gain, depression, low energy and cold intolerance. High thyroid levels (hyperthyroidism) cause “hyper” energy levels, a feeling of being too warm all the time, and persistent weight loss. But it is hypothyroidism, or low thyroid, that is most common in women during the perimenopausal and postmenopausal years; in fact, some 26% of women in or near menopause are diagnosed with hypothyroidism—and this is the period when breast cancer begins to rise sharply!
In the best-selling book, What Your Doctor May Not Tell You About Menopause, Dr. John Lee relates that as he learned more about the condition of estrogen dominance, it became apparent that the use of thyroid supplements among his women patients was especially common in those with estrogen dominance. He realized this was because when estrogen is not counterbalanced with progesterone, the estrogen buildup actually blocked thyroid hormone from being delivered to the cells of the body. Physiology tells us that this is because high estrogen levels increase proteins (e.g. thyroid binding globulins) that actually bind up thyroid hormones and inactivate them, thus making them unavailable to the body. Persistent estrogen dominance creates a vicious cycle of lowered thyroid function that sets women up for an increased risk of breast cancer. Dr. Lee found that “nine out of ten times,” when he used natural progesterone therapy in these patients, its “anti-estrogenic” balancing powers restored normal thyroid activity. Over 30 years of practice, he rarely saw a case of breast cancer among his patients. Here again, all signs point to estrogen dominance.
Vitamin D is in fact, not a vitamin at all but a hormone that is synthesized through the action of sunlight upon precursors (i.e. the substances from which hormones are derived) within the skin. Undiagnosed vitamin D deficiency is now considered to be epidemic among the elderly who stay indoors much of the time, and those living in northern climates where there is less sunshine per day and people tend to wear more clothing. Studies indicate that widespread vitamin D deficiencies are increasing risk for cancers of the colon, pancreas, prostate, ovaries and breast, and that people living at higher latitudes are more likely to die from these cancers, as compared with people living at lower latitudes. (Cancer Epidemiol Biomarkers Prev 2006). People of darker skin, the obese, and younger children also tend towards a deficiency of vitamin D. Scientists say that vitamin D’s anti-cancer actions lie in its ability to stop the uncontrolled growth of cells and encourage their natural differentiation and death (apoptosis), before they can mutate and become cancerous. The action of vitamin D is also breast protective because it can inhibit the blood supply that feeds tumors in malignant breast tissue.
High sunlight exposure, because it promotes the formation of vitamin D in the skin, has been associated with a reduced risk of breast cancer. In a recent study, researchers from Mount Sinai Hospital in Toronto studied 972 women with newly diagnosed invasive breast cancer and compared them with healthy women. (Cancer Epidemiol Biomarkers Prev 2007) The women in the study were interviewed to assess their vitamin D-related exposure, e.g., outdoor activities, use of sunscreen, dietary sources like cod liver oil, and milk consumption. It turned out that more frequent sun exposure during adolescence was linked to a 35% reduction in breast cancer risk later in life. Lower risk was also linked to cod liver oil intake, and drinking at least ten glasses of milk per week. The study suggests that vitamin D-related exposures during the teen years and early adulthood when the breasts are developing, may be more important than later exposure. This information provides a clear opportunity for early breast cancer prevention!
Another study in Norway found that the survival outlook for women diagnosed and treated for breast cancer was 15–25% better in the summer vs. the winter. A recent study reported in the prestigious American Journal of Clinical Nutrition, found that postmenopausal women who increased their vitamin D intake by 1100 IU of vitamin D3 (the active component) reduced their relative risk of cancer by 60–77% (Am J Clin Nutr 2007)—a pretty compelling reason to make sure your vitamin D levels are well within normal range!
Experts around the world are now saying that the recommended daily allowances (RDAs) are actually inadequate, and need to be increased to a minimum of 800 IU of vitamin D3 taken daily, while even higher doses may be physician recommended. Unless a person eats oily fish frequently, it is difficult to obtain that much vitamin D3 on a daily basis from dietary sources. Studies indicate that levels of vitamin D below 20ng per milliliter are associated with a 35–50% increased cancer risk. Testing D levels in blood serum or blood spot is highly recommended, and is a simple way to determine deficiency in the absence of telltale symptoms.