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Hormonal Havoc

How hormones in medication, pollutants and food may affect breast cancer

Stacey Peters of Tinley Park found a lump in her breast during a self-exam 8 years ago, when she was 24 years old. The lump turned out to be Stage II breast cancer. Peters had a lumpectomy, radiation and stem cell therapy, but her cancer spread to her liver and brain. She has undergone a variety of treatments because each time the cancer changes her doctors must switch gears to fight the disease.
    Being diagnosed at such a young age and without a family history of breast cancer, Peters’ situation illustrates the frightening seriousness of breast cancer and the swiftness and unpredictability with which it can strike.
    “Once you have cancer, it doesn’t matter what caused it,” Peters says.
    Prevention of this deadly disease, as a result, takes on paramount importance. According to the American Cancer Society, breast cancer is the second leading cause of cancer death in women. Approximately 178,480 women in the United States will be found to have invasive breast cancer this year, and roughly 40,460 women will die from the disease this year. The chance of a woman having invasive breast cancer some time during her life is about 1 in 8.
    Peters’ cancer is ER/PR-positive, which means that the cancer has receptors for estrogen and progesterone and these hormones send signals that cause the cancer to grow. This type of cancer is often responsive to hormone therapies, which block the receptors and can thus stop or slow the cancer’s growth.
    “At least 60 percent of breast cancers grow in the presence of estrogen,” says Dr. Marisa Weiss, the president and founder of Breastcancer.org and a breast cancer oncologist with an active practice near Philadelphia. “It’s not just estrogen
that’s naturally in your body, but also estrogen that you’re exposed to [in the environment].”
    Research has uncovered a strong link between hormones and breast and other cancers. Some hormones are produced naturally in the human body, and they send chemical “messages” that control growth, development and reproduction. There are also chemicals that are “hormonally reactive,” which means that they act as a hormone once in the body or intensify the effects of naturally occurring hormones. Besides being part of normal body functions, hormones can also be introduced through medication, the environment and food.

    Many women take birth control pills or Hormone Replacement Therapy (HRT) at different times in their lives. The active ingredients in both of these medications are hormones, which raises concerns when one considers the link between hormones and some cancers.
    The American Cancer Society points to studies that have found that women who take birth control pills have a slightly greater risk of breast cancer than women who have never used them, but the level of risk decreases to normal levels in women who stay off birth control pills for 10 years.
    Similarly, taking HRT puts women at a roughly 25 percent increased chance of developing breast cancer, Weiss says. In other words, the normal level of risk associated with developing breast cancer is 12 percent, and that increases to 15 percent with HRT. When a patient stops taking HRT, though, the risk goes back down to normal levels, Weiss says.

    Another source of hormone-effect comes from “hormonally active pollutants,” Weiss says. Pesticides are one such source. The pesticide DDT breaks down to DDE, which can have an estrogen-like effect. DDT is outlawed in the United States, but some countries can still use it on fruits and vegetables, which they export to the United States. Some fertilizers also contain hormonally active pollutants, as does the groundwater in some regions, which can also affect the plants that draw on those water sources.
    The level of hormones from these sources is usually low, but the effect can be cumulative.
    “It’s like when someone keeps poking you and you get pissed off,” Weiss says. “The fact is that low levels of hormones can have an influence in your body.”
    To stay healthy, Weiss recommends trying to reduce sources of hormones and hormonally active compounds.  She says that steel-lined or glass water bottles eliminate the chemicals that plastic water bottles release as they break down. She says to avoid plastics, including aluminum and tin cans that have a plastic liner that food and drinks are exposed to. Weiss also champions locally grown, organic and fresh sources of food to reduce exposure to pesticides and other pollutants.

    Hormones and chemicals that mimic hormones in the body are also stored in fat, which is one reason researchers have
linked high levels of body fat and cancer. Additionally, fat itself is hormonally active, which means it produces and responds to hormones. With so many Americans being overweight or obese, this is a source of great concern for medical professionals.
    “With this country’s obesity, I am worried about a higher incidence of breast cancer,” Weiss says.
    Obesity has also been linked to experiencing menarche, females’ first menstrual period, earlier in life. Earlier age of menarche has also been linked to a higher risk of breast cancer, says Dr. T. Colin Campbell, the Jacob Gould Schurman Professor Emeritus of Nutritional Biochemistry at Cornell University and author of The China Study (Benbella Books, 2006).
    Women who enter menopause later in life are also at an increased risk of breast cancer, according to Campbell. As such, the longer a woman is between menarche and the onset of menopause, the higher her risk of developing breast cancer.
    Campbell says that his research found that American women start menses approximately 5 years earlier than rural Chinese women and experience menopause about 4 years later than the same group.
    In The China Study, Campbell writes, “Because the length of the reproductive life of a Chinese woman is only about 75 percent of that of the British (or American) woman, this means that with lower estrogen levels, the Chinese woman only experiences about 35 to 40 percent of the lifetime estrogen exposure of British (and American) women. This corresponds to Chinese breast cancer rates that are only one-fifth of those of Western women.”
    Weiss also confirms the link that research has found between menarche and breast cancer risk.
    “Obesity starts the menses earlier, which is a risk factor for breast cancer,” Weiss says.

    Since obesity increases one’s risk of breast cancer, eating a healthy diet and staying physically active are considered two of the best ways to reduce the risk of disease.
    Campbell says that a diet of whole foods from mostly plant sources can have a very positive impact on overall health. In fact, Campbell says that as he conducted research throughout his career, but especially in relation to his findings in The China Study, he started to see a strong connection between the development of disease, including cancer, and the consumption of animal proteins.
    Campbell was raised on a dairy farm in northern Virginia and spent much of his education and early career working on issues of “animal nutrition”—advocating the consumption of foods from animal sources and researching ways to increase the production of meat, eggs and milk for food.
    “I thought the good old American diet was the best there was,” Campbell says.
    But, according to Campbell, he found that the research shows an association between the consumption of meat and dairy and the incidence of cancer. This led to a turning point in not only his work, but his approach to his own health and that of his family. He says that proteins in meat and dairy, in particular, contribute to elevated risk of reproductive cancers—not only cancer of the breast, but also ovarian and prostate cancer.
    “In my experience, when all this information is put together, it’s very clear to me that animal-based foods increase the risk of breast cancer,” Campbell says.
    Campbell’s conclusion seems to be supported by a study from researchers at Brigham and Women’s Hospital and Harvard Medical School, published in the November 13, 2006 issue of the Archives of Internal Medicine. Researchers found that eating more red meat may be associated with a higher risk for hormone receptor-positive breast cancers in pre-menopausal women. In this study, researchers examined the link between red meat consumption and the development of breast cancer in 90,659 nurses between the ages of 26 and 46. They split the women into five groups based on how much red meat they ate. The group that ate the most red meat had nearly double the risk for hormone receptor-positive cancer compared to the groups that consumed the least red meat.
    “The reason why the amount of red meat consumed by a pre-menopausal woman was related to her breast cancer risk is unknown, but this study shows that it has a strong association and that more research should be done to further explore this connection,” said Eunyoung Cho, the study’s lead author and assistant professor of medicine at Harvard Medical School.
    Campbell’s views are controversial among many experts, and the meat and dairy industries disagree with those who say that a diet that includes animal proteins increases the risk of cancer.
    David Grotto is a registered dietician and national spokesperson for the American Dietetic Association. The ADA Foundation is supported by Kraft Foods, The Cattlemen’s Beef Board and The National Cattlemen’s Beef Association, according to the ADA website. Grotto says that the argument for meat or milk consumption leading to cancer is weak.
    “Milk has been targeted because of raising insulin growth hormone (IGF-1), which theoretically may spur on growth of cancer cells,” Grotto wrote via email. “But in other studies, dairy may be protective for breast cancer, possibly due to its conjugated linoleic acid content (CLA). The milk/hormone connection lacks research to support the theory. This is also true with meat and breast cancer.”
    Grotto does concur that maintaining a normal weight and balanced diet are essential for overall health, including cancer prevention.
    “The best advice, based on credible science, happens to be the 2005 dietary guidelines for Americans, which encourages nutrient-dense food consumption, watching calorie intake, while encouraging exercise,” Grotto says. “Obesity is the number one concern regarding risk for breast cancer, not any one food or food group.”
    Though they disagree with some of the details, many experts do seem to agree that diet holds a lot of power over maintaining good health.
    “I do believe we’re beginning to gain an appreciation for the fact that energy balance and a good diet are beneficial [for preventing cancer],” says Dr. Susan Gapstur, a professor of preventive medicine at Northwestern University’s Feinberg School of Medicine.
    Campbell agrees.
    “[Diet] offers a lot of promise, in terms of preventing disease, advancing health and reversing advanced heart disease,” says Campbell. “There’s a beautiful message lying there: we can use food to create health.” o

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Published: October 14, 2007
Issue: November 2007