Role of differentiation in the pathogenesis and prevention of breast cancer

Introduction The prevention of breast cancer, whose incidence continues increasing in industrialized nations, has been hindered by the lack of identification of a specific agent or mechanism responsible of its causation, despite extensive and worldwide clinical and experimental research (John & Kelsey 1993, Russo J & Russo IH 1994, Parker et al. 1996, Trichopoulos et al. 1996). Nevertheless, this research has identified conditions associated with a greater risk of developing breast cancer. Thus, the combination of certain external factors, such as diet and socioeconomic status, and history of exposure to ionizing radiation, with not as yet well-defined internal factors, namely specific endocrinological, reproductive and familial conditions or genetic predisposition, profoundly influence the risk to women of developing breast cancer in their life-time (Parker et al. 1996). Faithful to the goal of preventing breast cancer, our research has focused on those factors associated with a lower risk of disease development. The