Breast cancer is one of the most common cancers seriously afflicting women in the United States. Of the one million incident cases that are reported annually there are approximately 193,000 new cases of breast cancer (Greenlee, 2001). Although significant advances have been made both in early detection and treatment of breast cancer, the impact of these on reduction in mortality has been modest (Peta, 2000). Furthermore, despite data implicating diet and other environmental risk factors, no lifestyle changes have yet been shown to significantly reduce the risk of breast cancer. Therefore, chemoprevention of breast cancer is a worthwhile approach to reduce the incidence of breast cancer.