Herbs With Estrogen Action May Raise Cancer Risk< April 23, 2002 > Some commonly used herbal treatments may further increase the risk of breast and uterine cancer for women already predisposed to those diseases. That is the suggestion of a new animal study presented recently at the annual meeting of the American Association for Cancer Research in San Francisco. Researchers from the University of Pittsburgh Cancer Institute offer new evidence that herbs such as red clover and motherwort—traditionally used for gynecological complaints—as well as saw palmetto and rhodiola rosea root can have such a strong estrogenic effect they could increase the risk of estrogen-related cancers. "Despite the fact that these are plants, we demonstrated considerable estrogenic activity—including the ability to bind to estrogen receptors" in much the same way as natural estrogen or estrogen replacement does, says study author Patricia Eagon, an associate professor of medicine at the University of Pittsburgh. In addition, Eagon found that extracts of maca root, cramp bark, and turmeric root also exhibited modest estrogenic activity. While all the plants can successfully be used to ease a wide variety of symptoms, particularly those associated with menopause and the corresponding drop in natural estrogen levels, Eagon says women who want to limit estrogen exposure should think twice before using these herbs. "The activity is there, so if you are avoiding estrogen for any reason, you should probably not use these herbs," Eagon says. This is especially true for women at risk for estrogen-sensitive cancers, particularly in the breast and the uterus. For alternative medicine expert Dr. James Dillard, the findings are an important caution. He adds, though, that they should be viewed in the proper perspective. "First, what holds true for rats doesn't always true for humans, so you can't make that automatic leap from an animal study to human application," says Dillard, clinical medical advisor at the Rosenthal Center of Alternative and Complementary Medicine at Columbia University. That said, he also suggests women should err on the side of caution and approach the use of these herbs judiciously, particularly if they are at risk for any estrogen-related cancers. "If a woman is avoiding hormone replacement therapy because she is concerned about exposure to estrogen, then she should also avoid these herbs—at least until we can confirm or refute these findings in human studies," Dillard says. The study was an animal experiment using rats that had their ovaries surgically removed. This, Eagon says, automatically deprived the rats of their natural estrogen supply. However, when these same rats were exposed to the various herbs in the study, Eagon reports, researchers could again document measurable levels of estrogenic activity. Specifically, the estrogen in the plants was able to bind to estrogen receptors in the rats, acting much like a true hormone. In one respect, the findings show these estrogenic botanicals may have strong clinical applications, such as the ability to reduce some menopause-related symptoms. However, "it might be wise to avoid these herbs in conditions where estrogen is contraindicated," Eagon says. This would include women with a strong family history of breast or uterine cancer, or those who may have already had one or more bouts with either disease, she says. Always consult your physician for more information. Online Resources:(Our Organization is not responsible for the content of Internet sites.) American Association for Cancer Research |
For more information about estrogens effects on the female body, please visit our Women's Health or Gynecological Health clinical content modules. High Estrogen Levels in Post-Menopausal Women Tied to Breast CancerWomen who have relatively high levels of natural estrogen after menopause are twice as likely to develop breast cancer. The same may hold true for those with high levels of other sex hormones, including androgens such as testosterone. That is the sobering news reported in the Journal of the National Cancer Institute by the International Endogenous Hormones and Breast Cancer Collaborative Group. The group is a panel of physicians and researchers who analyzed data from nine previous breast cancer studies involving some 2,400 women from the United States, Italy, Japan, and England. "There were a number of smaller studies indicating that post-menopausal women with higher estrogen levels were at greater risk for breast cancer. But this analysis pooled all the data from all the studies to demonstrate the increased risk in a fairly large group," says study co-author Joanne F. Dorgan, a researcher at Fox Chase Cancer Center in Philadelphia who was an epidemiologist with the National Cancer Institute when the study was conducted. It is also the first study to find that testosterone and DHEA are also linked to increased risk of breast cancer, regardless of estrogen levels. DHEA is a hormone that can be converted by the body into estrogen, testosterone, or both. Breast cancer expert Dr. Clifford Hudis says he is not surprised by the findings, but cautions scientists still do not know the precise role hormones play in breast cancer. "We still don't know if estrogen is a precipitating factor, causing the cancer to develop, or an exacerbating factor that simply causes a tumor that is already there to grow more rapidly. This study, as good as it is, doesn't answer this question," says Hudis, chief of the Breast Cancer Medical Service at Memorial Sloan-Kettering Cancer Center in New York City. Indeed, it is possible that estrogen, as well as testosterone, could be indications of other causes that are the true link to the cancer—including body fat, which has already been cited in numerous studies as a risk factor for breast cancer. Perhaps not coincidentally, once ovaries stop functioning, as they do after menopause, much of a woman's estrogen supply comes from fat cells—something Dorgan says her group plans to examine more closely in a subsequent analysis of the data. Always consult your physician for more information. |