The Vermont Breast Cancer Surveillance System is proposed in this cooperative agreement application to become part of the multi-site National Cancer Institute Breast Cancer Surveillance Consortium. Our goal is to organize a multi-disciplinary group of breast cancer investigators joining with researchers in other Consortium sites and NCI staff in conducting collaborative breast cancer surveillance research. As the most rural state in the nation, Vermont is well suited to balance more urban sites currently represented in the NCI Consortium. In addition, with an ongoing state-wide mammography-pathology registry coupled with a mandated state cancer registry based on the SEER model, our site is well prepared to keep pace with the present NCI Consortium sites in gathering and analyzing surveillance data. Specific aims of this application are: (a) to establish a comprehensive, quality controlled, state-wide surveillance system that will access existing records and collect new information from mammography facilities, pathology laboratories, and a population-based cancer registry; (b)to foster breast cancer research collaborations and interactions among basic researchers, clinical researchers and applied researchers in Vermont and in the NCI Breast Cancer Surveillance Consortium; and (c) to examine the operational aspects of breast cancer screening and diagnosis by conducting systematic research designed to assess the effectiveness, efficiency and cost of screening programs and diagnostic techniques as they relate to the reduction of morbidity and mortality from breast cancer. Specific areas of proposed research include the development of a medical decision model to improve breast screening outcomes (Research Project #1) and evaluating the application of ultrasound guided breast biopsy and clinical outcomes (Research Project #2).