Because isoflavone and the breast cancer drug tamoxifen both bind to estrogen receptors, there has been concern that soy could interfere with the treatment; but the JAMA study found that for women who had low to moderate soy intake while on tamoxifen, there was an increased rate of survival, and for women on tamoxifen who had high soy intake, the soy did not seem to affect their prognosis one way or the other
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