LOS ANGELES (July 29, 1999) -- Researchers at the Center for Women's Health at Cedars-SinaiMedical Center are launching a clinical trial to assess whether eating certain plant compounds can have positive effects on the lining of the uterus. These plant compounds, called "isoflavones," are found in particularly high amounts in clover and soybeans. Isoflavones are also known as "phytoestrogens" because they have been found to have a variety of mild hormonal actions within the human body.
Georgina Hale, M.D., a visiting internist from Australia doing post-doctoral clinical research at Cedars-Sinai, said that this is the first study of its kind specifically directed at the effects of isoflavones on the human endometrium.
Because the normal endometrium is constantly changing and is highly responsive to hormonal fluctuations, it provides an excellent environment in which to detect the impact of isoflavones, said Dr. Hale. During the normal menstrual cycle, the endometrium grows thicker as its cells multiply. These cells are then shed during menstruation, after which the process begins again.
Estrogen, one of the hormones produced by the body, is primarily responsible for directing endometrial cells to multiply or proliferate. While proliferation is necessary during the "build-up" phase of the endometrium's cycle, estrogen's proliferative effects need to be constrained by other hormones, such as progesterone. If estrogen stimulation continues unchecked, endometrial hyperplasia can result. This condition is a known risk factor for the later development of endometrial cancer.
There is evidence that phytoestrogens in the diet may help counteract the proliferative effects of estrogen. "In Asia, where there is a high dietary phytoestrogen intake, there is also a low incidence of endometrial cancer," said Dr. Hale. "Asian women have an endometrial cancer rate as low as one in 100,000 but women in the United States have rates as high as 20 in 100,000. Furthermore, when Asian women adopt a Western diet, their endometrial cancer rates increase."
Claude Hughes, M.D., Ph.D., a specialist in obstetrics and gynecology, and director of the Center for Women's Health, has been involved in earlier studies on the impact of phytoestrogens on the endometrial cells of monkeys and rats. In those two studies, soy-based phytoestrogens appeared to counteract estrogen's proliferative effects, although another study conducted elsewhere failed to support this finding in rats. "The benefits of phytoestrogens look promising in monkeys, mammals that are similar in many ways to humans, but the studies in rodents were inconclusive. It seemed to us that the next step in determining the value of phytoestrogens in women would be to analyze actual human tissue."
Women who volunteer to participate in the study will be given a thorough gynecological examination at the beginning of the study and another at the conclusion. This will provide "before and after" observations of endometrial proliferation. Ultrasound studies will be used to view the uterine artery and to gauge the thickness of the endometrium. Even more definitive information will come from biopsies of endometrial tissues. From these, the researchers will be able to look for microscopic changes and measure levels of Ki67 antigen, a substance that tends to increase with proliferative activity.
During their three to four months of participation, women in the study will be asked to follow a soybean product-restricted diet and take a single tablet each day. This tablet will contain either clover-based phytoestrogens or placebo. Only the study's sponsor, Novogen, an Australia-based manufacturer of dietary supplements, will have the code identifying which patients receive which pills.
Women who volunteer for the study will receive a health screen, endometrial biopsy and ultrasound examinations at no charge, as well as a monetary award for completion of the study. Participants will also receive health maintenance information from physicians and dietitians. For example, certain lifestyle factors, such as diet and exercise for weight management, have been found to reduce estrogen levels and the associated risk of endometrial cancer.
The study is open to women between 45 and 50 years of age who are in good health, still having menstrual cycles, and not currently taking hormone replacement therapy or the oral contraceptive. Those interested may contact Dr. Hale at the Cedars Sinai Center for Women's Health at 310-855-3291 or 310-855-7432 for details on additional requirements and benefits of participation.
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