Breast cancer remains a leading cause of cancer death among women in the United States. More than 180,000 new cases of invasive breast cancer are diagnosed each year, and more than 40,000 women die of the disease. Recent years, however, have seen improvements in survival attributed to better treatment and diagnosis. Research efforts have been directed toward better treatment, preventive strategies, and early detection. Although mammography has been the mainstay of early detection, its limitations are well recognized and the search for more effective technologies for detection has been receiving increased attention. As part of this increased attention, the Institute of Medicine (IOM) convened a committee to examine the current state of the art in early breast cancer detection, to identify promising technologies, and to examine the many steps in medical technology development and the policies that influence their adoption and use. The IOM committee consisted of a 16-member interdisciplinary group with a wide range of views and expertise breast cancer, medical imaging, cancer biology, epidemiology, economics, and technology assessment. The committee examined the peer-reviewed literature, met four times, held two workshops that dealt with new technologies as well as policies related to their adoption and dissemination, and consulted with experts in the field. Early detection is widely believed to save lives by facilitating intervention early in the course of the disease, at a stage when cancer treatment is most likely to be effective. This concept, however, belies a number of complexities, not the least of which is the need to understand the basic biology of breast cancer. The committee recognized the need for research on the natural history of breast cancer to more clearly define the significance of early lesions, the need for the development of biomarkers, and the importance of assessing the effectiveness of new technologies in decreasing morbidity and mortality. This report describes many novel technologies that are being developed for the purpose of early breast cancer detection, as well as recent technological advances in detection modalities already in use. Because the many technologies that the committee examined were at different stages of development and thus the evidence of their accuracy and effectiveness varied, the committee found it difficult to predict which of the many new technologies were likely to play a role in the future .