Developing phytoestrogens for breast cancer prevention.

Breast cancer is one of the most common types of cancer in women, and is the second leading cause of cancer-related deaths in the United States. Chemoprevention using phytoestrogens (PEs) for breast cancer may be a valid strategy. PEs are phytochemicals with estrogen-like structures and can be classified into four types: isoflavones, lignans, stilbenes and coumestans. They are widely distributed in diet and herbs and have shown anti-cancer activity via mechanisms including estrogen receptor modulation, aromatase inhibition, and anti-angiogenesis. Genistein, daidzein and resveratrol are some of the most studied PE examples. Quality control in product manufacturing and clinical study design is a critical issue in developing them as clinically effective chemopreventive agents for breast cancer.