Soy, isoflavones and breast cancer

Soy is a major source of isoflavones. Isoflavones are phytoestrogenic components. They may bind to estrogen receptors but they also exert other physiological effects. Case-control and prospective studies show an inverse association between soy isoflavones intakes and breast cancer risk, mainly in post-menopausal women. The role of an early exposition during childhood and adolescence seems important. Most of the studies show a strong inverse association between soy and isoflavones intakes and recurrence or mortality for breast cancer, even under tamoxifen therapy. The Guidelines could take into account these new data.