Early breast cancer represents an area in which advances in understanding of epidemiology, natural history, and tumor biology have merged with advances in surgery and technology to bring about some of the most significant reductions in mortality from cancer in this century. Breast cancer can be viewed as a collection of many different diseases with distinct levels of biologic behavior that are based on individual host-tumor interactions, which are in turn governed by a multitude of genetic, environmental, and hormonal variables. The key to many of the persistent questions about carcinoma of the breast and its management may lie in its earliest stages, for it is here that the origins of malignancy lie. The current multimodality approach to its detection and treatment reflects the complexity of this disease, as well as the need for a thorough understanding of all aspects of its biology. The physician involved in the management of early breast cancer must be committed to such an understanding, as well as to a rational integration of these various factors with the specific psychological and emotional makeup of the patient in order to achieve optimal results and continue advancing the frontiers of development.