I found this on the link web site below
http://www.H
ormonecme.Org/product/medcasesframe.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
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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
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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
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Lancet. 1997;350:990-994.Pmid: 9329514
8kazi a, et al. Inhibition of the
proteasome activity, a novel mechanism
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Biochem pharmacol. 2003;66:965-976.
Pmid: 12963483
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11075748
11adlercreutz h, mazur w. Phytoestrogens
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12allred cd, et al. Dietary genistein
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