Soy Isoflavones

I am interested in learning about the effects of increasing soy in one's diet.  I have read that genistein in soy isoflavones might prevent estrogen from reaching breast cancer cells by blocking access to estrogen recptors.  I'm not quite sure what this means??  If this is so, wouldn't it reduce the risk of taking conjugated estrogens?  In other words, couldn't a post-menopausal woman take the lowest dose of Premarin and also supplement with soy isoflavones, thus getting the benefits of estrogen therapy without worrying as much about breast cancer?
Thank you.

[CCF-RN,MSN-JS]

Dear MaryFran: The debate continues as to whether hormone replacement therapy does increase one

[maryfran]

Thank you, doctor, for your response.  One more question, please.

Do you know whether taking a soy isoflavone supplement would interfere with or cancel out the benefits while also taking Premarin?

Thank you.