It doesn't kill as many people as heart disease, but breast cancer is still a serious threat to women (and to some men). In 1999, about 176,300 new cases of breast cancer were likely to be diagnosed in the U.S. (1,300 of these amoung men).

A report from the National Cancer Institute (NCI) estimates that about one in eight women in the United States (approximately 12.6 percent) will develop breast cancer during her lifetime, and one of every 28 women has a risk of dying from it. Hispanic women have a faster rising breast cancer rate than other women, and American Indian and Alaskan Native women have higher incidence and lower survival rates thatn many other groups. As Asian and Pacific Islander women become Westernized, their risk goes up and Ashkanazi Jewish women have a higher incidence of gene mutations that increase risk. African American women are more likely than others to die from the disease. Also, risk increases with age. Hormone replacement therapy, too, has been linked to a slight increase in breast cancer risk (though it has benefits as well for many women).

Fortuanately, greater use of mammograms helps detect cancer early and the five-year relative survival rate is rising. Of course, prevention is the best defense. Living healthfully - eating a diet high in plant-based foods, avoiding tobacco, limiting alcohol consumption and exercising, among other good habits - is crucial to staving off this killer. Supplements also play a role in preventing - and even stopping the progression of - breast cancer, and increased chemoprevention research is turning up some promising results.

What Is Breast Cancer
Breast cancer is marked by the uncontrolled growth of cells in breast tissue as a result of gene mutations, which eventually overwhelm the body's defenses. Few people truly have an inherited susceptibility to the disease. Environmental factors play a big role. Free radicals that damage DNA can cause cells to act abnormally and proliferate rampantly, sometimes resulting in tumor growth. Estrogen can even encourage the proliferation of cancer cells. This is because the hormone normally controls breast cell growth. Estrogen can even encourage the proliferation of cancer cells. This is because the hormone normally controls breast cell growth when it attaches to estrogen receptors. That's natural, but the problem arises when estrogen causes abnormal breast cells to divide faster than normal cells, which can result in tumor formation.

Environmental exposure to chemicals that are similar in structure to estrogen (xenoestrogens), and therby recognized by the body as estrogen, or high levels of circulating estrogen, can lead to this predicament. However not all compounds that mimic estrogen are deleterious; phytoestrogens found in plants even appear to have a protective effect. (The drug Tamoxifen has been proven to reduce the incidence of breast cancer in many high-risk women, but it also increases the risk of endometrial cancer and thromboembolis.)

Soy Isoflavones
By now, virtually everyone knows that phytoestrogens called isoflavones found in soy and other plant foods (and supplements) can protect against breast cancer. Genistein is the primary isoflavone in soy foods proven protective against cancer in numerous research studies. Isoflavones are considered antiestrogens as well as proestorgens because of their dual role: they act like estrogen by attaching to estrogen receptors, yet they signal the body to actually produce less estrogen as a result. By attaching to receptors and acting as very weak estrogens, isoflavones encourage more rapid differentiation of mammary gland cells (that's a good thing). This is one mechanism by which they have been proven to inhibit the growth of breast cancer cells in animal studies. Regular isoflavone intake early in life may offer the most benefits, according to some researchers.

There is some concern that isoflavones could potentially encourage cancer growth due to their estrogen-like activity, but the debate continues. This possible relationship isn't consistent with the obervation that women in Asian countries who consume large amounts of soy foods have much lower breast cancer rates than American women who tend toward much lower isoflavone intake, nor does it jibe with what we know bases on the biological activity and most research results thus far.

Tori Hudson, N.D., professor of gynecology at the National College of Naturopathic Medicine in Portlan, OR, and author of the Women's Encyclopedia of Natural Medicine (Keats, 1999), considers 50-150 mg. of soy isoflavones per day a safe intake, as that amount is commonly consumed on a daily basis in countries where soy is a staple of the diest and hasn't been linked to increased breast cancer risk. But some practitioners are more cautious in their recommendations to women who are at high risk of breast cancer or who have already been diagnosed with the disease. It's important to remember that phytoestrogens are much, much weaker than true estrogen, too.

Future studies on large numbers of women who take large amounts of soy starting agter menopause and studies amoung women with breast cancer who take soy after they're diagnosed should shed more light on the rlationship between isoflavones and breast cancer, noted Hudson. Checking labels for isoflavones content, particularly in powdered soy protein mixes and other functional foods, is crucial to choosing the best products. Soy foods are excellent sources of genistein, but supplements may be more convenient at times. The guidance of a natural health practitioner can help women determine the best isoflavone intake for them.

Conjugated Linoleic Acid
Conjugated linoleic acid (CLA) is mainly derived from dairy products and has been shown in animal and in vitro studies to exhibit strong anti-tumor activity. In a study with immunodeficient mice inoculated with breast cancer cells, two weeks of dietary CLA inhibited local tumor growth significantly. CLA also discouraged the spread of breast cancer cells to lungs, peripheral blood and bone marrow in the study, suggesting that CLA can block local, human breast cancer growth as well as its systemic spread independent of the host's immune system.

Additional studies should help clarify the mechanisms of CLA's protective effect. According to Dr. Delbert Dorscheid, M.D., Ph.D., a cancer researcher in Pulmonary and Critical Care Medicine at the University of Chicago, the most dramatic impact of CLA may, in fact, be on breast cancer reduction. A growing number of studies have demonstrated an inverse relationship between CLA tissue levels and breast cancer incidence, says Dorscheid.

Selenium
Selenium is an antioxidant and anticarcinogenic mineral that can modify glutathione status and that of other enzymes by blocking harmful lipid peroxidation in membranes of cancer subjects. One recent study on rats with mammary tumors who were supplemented with selenium for 24 weeks demonstrated that the antioxidant corrected abnormal changes in glutathione turnover and other enzymes. Glutathione is a powerful antioxidant, so maintaining optimal levels is best for fighting cancer (antioxidants help clean up circulating free radicals that damage cells and increase cancer risk). Other study findings support this relationship; breast cancer patients have