Breast Cancer Risk and Chemoprevention

The purpose of this chapter is to discuss the potential role of retinoids in breast cancer chemoprevention. Chemoprevention may be defined as the use of natural substances and their synthetic analogs or of other chemicals to reduce the likelihood of cancer development. For epithelial cancers, which account for the majority of human malignancies, chemoprevention consists of intervention measures taken during the development of the neoplastic process up to the stage of in situ carcinoma. Excellent reviews [8, 32, 50] have discussed this topic since the concept and the term were introduced a decade ago [73]. However, the question of dose of chemopreventive agents in relation to the stages of tumor formation has not been adequately addressed. This issue will be specifically considered from a clinical perspective based on an overview of experimental, epidemiologic, and clinical evidence.