Preventive intervention in breast cancer, but when?

After an introductory note on primary preventive intervention of breast cancer during adulthood, the author defends and extends a hypothesis that relates most of the known risk factors for this disease to the development of preneoplastic lesions in the breast. If changes in lifestyle concerning nutritional and/or reproductive risk factors during puberty and adolescence would turn out to be unacceptable socially, an alternative approach might be found in chemoprevention based on cell differentiation.