
<b>Phytoestrogens</b> 
are bioactive substances present in plant products which, when eaten, act like estrogen in the human body.  Usually the estrogenic influence is weaker than animal estrogen products.  Soy products, especially tofu, are known to contain phytoestrogens.

Women who have estrogen receptors on their tumor cells may have tumors that are stimulated by estrogens.  The risk factors for uterine cancers are very much involved with estrogen levels and stimulation of the cells.  
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In the premenopausal woman, her ovaries produce estrogen to provide high levels in her body.  For these women, competition between the phytoestrogen and estrogen for the same estrogen receptor might result in a LESSER stimulation of estrogen receptor cells, because phytoestrogens are weaker stimulators.  
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In the postmenopausal woman, whose estrogen levels are low, and those who are on aromatase inhibitors whose estrogen levels are very low, phytoestrogens might provide a higher level of estrogenic stimulation than there otherwise would be.  Furthermore, specific phytoestrogen receptors exist as well.  The subject gets complicated.
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Whether postmenopausal women with estrogen receptor positive cancers should avoid phytoestrogens is not known for sure.   However, many oncologists recommend caution in use of phytoestrogens in the postmenopausal woman with estrogen receptor positive cancer.  
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Which creates a problem for women who wish to adopt a vegan diet, as the major complete protein in those diets is tofu.  However, a very reasonable anti-cancer diet can be constructed using fish, egg white, and nonfat dairy as protein sources.  

For more information:
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<b>Red Meat</b>
Many studies show an increased risk of some cancers in people who eat more red meat as compared to those who eat less.  
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There is also an increased risk of uterine fibroids with those who eat more red meat [beef and ham], and a protective effect from green vegetables.  
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It is unknown what the factors in red meat consumption are that are responsible for this.  One factor might be hormone levels in the meat. 


<b>Being Overweight</b>
Postmenopausal women do not have estrogen made in their ovaries.  They make estrogen in their fat tissue, and muscle and breast tissue, from hormonal precursors produced by the adrenal glands.  Postmenopausal women who are overweight will make more estrogen.   There is evidence accumulating that for estrogen sensitive tumors survival is worse in overweight women.
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doctordee
December 2003