I found this on the link web site below
http://www.Hormonecme.Org/product/medcases
frame.Asp
ask the expert
november 2003
question:
do you recommend that postmenopausal patients avoid the use of soy products if they are at high risk for breast cancer?
Response by Dr. Michelle p. Warren:
this is an important question, as more and more women are turning to soy and other natural substitutes for estrogen to treat menopausal symptoms. Of the women seeking "natural alternatives," 71% believe there are no risks involved and 62% believe such alternatives are equally or more effective for treating menopausal symptoms.1 for physicians, however, this optimism is tempered by the recognition that the dearth of evidence-based studies makes it difficult to ascertain the safety and efficacy of these products.2 the problem is further compounded by the fact that even among the published studies, the conclusions are not easily generalizable because of the lack of uniformity with regard to protocol, test dose, and type of soy product tested.
The possible protective effect of soy was first noticed among asian women. These women, whose diets were high in soy, were found to have a reduced risk of breast cancer compared to women in the us and other western countries.3 in addition, since 1991 several case-controlled studies have reported that phytoestrogen consumption is associated with a decreased risk of breast cancer in pre- and postmenopausal women.4,5,6,7 the exact mechanism of soy's effect on breast tissue is not completely understood, but it has been suggested that the protective effect derives from the ability of genistein, a soy isoflavone, to induce apoptosis of solid tumor cells.8 this issue is further complicated, however, by the research indicating that genistein also acts on the estrogen-receptors (er-beta) found in breast tissue (particularly er-beta).9 in addition, in another model, it was suggested that the estrogen level in the tissue might modulate the cellular response. In women with high estrogen levels (premenopausal), isoflavones might act as an estrogen antagonist; in women with lower levels (postmenopausal), they might act as an estrogen agonist.10,11 the estrogenic effects of soy on breast tissue have been reported in a recent study indicating that genistein increased the growth of estrogen-dependent mammary tumors in rats.12 while this study was performed on female rats, the dose used was at a physiological level relevant to human exposure, and thus has important implications for women, particularly those at increased risk for breast cancer.
In conclusion, while the epidemiological studies appear to support the hypothesis that soy products are safe-and perhaps even protective with regard to breast tissue-the in vitro evidence suggests that the mechanisms involved are complicated and require further investigation. Until further research is done in this area, it is a good idea for postmenopausal women at high risk for breast cancer to consume only moderate amounts of soy.
Michelle p. Warren, md
wyeth professor of women's health
professor, obstetrics, gynecology, and medicine
medical director, center for menopause, hormonal disorders & women's health
columbia university, college of physicians and surgeons
new york, ny
november 2003
references
1adams c, cannell s. Women's beliefs about 'natural' hormones and natural hormone replacement therapy. Menopause. 2001;8:433-440.Pmid: 11723417
2warren mp. The effects of phytoestrogen supplementation in postmenopausal women. J soc gynecol investig. 2002;9:184-185.Pmid: 12113876
3messina m, barnes s. The role of soy products in reducing risk of cancer. J natl cancer inst. 1991;83:541-546.Pmid: 1672382
4lee hp, et al. Dietary effects on breast-cancer risk in singapore. Lancet. 1991;337:1197-1200.Pmid: 1673746
5wu ah, et al. Tofu and risk of breast cancer in asian-americans. Cancer epidemiol biomarkers prev. 1996;5:901-906.Pmid: 8922298
6yuan jm, et al. Diet and breast cancer in shanghai and tianjin, china. Br j cancer. 1995;71:1353-1358.Pmid: 7779738
7ingram d, et al. Case-control study of phyto-oestrogens and breast cancer. Lancet. 1997;350:990-994.Pmid: 9329514
8kazi a, et al. Inhibition of the proteasome activity, a novel mechanism associated with the tumor cell apoptosis-inducing ability of genistein. Biochem pharmacol. 2003;66:965-976. Pmid: 12963483
9mazur w. Phytoestrogen content in food. Baillieres clin endo metab. 1998;12:729-742.Pmid: 10384822
10vincent a, fitzpatrick la. Soy isoflavones: are they useful in menopause? Mayo clin proc. 2000;75:1174-1184.Pmid: 11075748
11adlercreutz h, mazur w. Phytoestrogens and western diseases. Ann med. 1997;29:95-120.Pmid: 9187225
12allred cd, et al. Dietary genistein results in larger mnu-induced, estrogen-dependent mammary tumors following ovariectomy of sprague-dawley rats. Carcinogenesis. October 24, 2003 [epub ahead of print].Pmid: 14578162
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