This proposal seeks a renewal of funding for ttie United States-based International Breast Cancer Study Group (IBCSG) Statistical and Data Management Center, a resource that contributes to International-US collaboration in the following areas: ?Access to the IBCSG clinical database of over 29,300 breast cancer patients enrolled in large-scale, randomized clinical trials with up to 30 years' maximum follow-up. ?Access to the IBCSG translational database of tumor-specific markers, host factors, gene arrays, and pathways; and the bio-specimen bank for over 12,000 patients. ?Expertise of statistical and medical investigators and collaboration in the IBCSG research agenda. This proposal will continue the successful enrollment of U.S. patients to IBCSG trials (especially of endocrine therapy for young women), as well as enrollment of IBCSG patients to U.S.-led trials. Such global collaboration is essential to accrue the number of patients needed to evaluate treatments tailored for breast cancer subpopulations and tumor subtypes. The IBCSG is uniquely positioned to conduct translational research in large randomized clinical trials with extensive clinical databases and an established and expanding bio-specimen bank. The primary goal of the IBCSG is to determine the best possible treatments for individual patients with breast cancer. The specific aims of this application comprise the major areas of research toward this goal. ?To provide US-based statistical and data management collaboration for the design, conduct, analysis, and reporting of IBCSG randomized clinical trials evaluating adjuvant therapies. ?To facilitate translational research by providing access to our bio-specimen bank, to our translational database from collected specimens, and to collaborate in the analysis of translational projects. ?To facilitate collaboration on database studies to identify and confirm the relationship between characteristics of breast cancer patients and response to adjuvant therapies. RELEVANCE: This resource gives NCI a cost-effective opportunity to significantly improve the understanding of treatment and prognosis of women with operable breast cancer. Many women are successfully treated with current therapies, but many still relapse and die of their disease. The tailored therapy trials and translational research plans in this proposal will facilitate progress to identify the best treatments for the individual patient.