The purpose of the Biostatistics Core is to provide professional expertise in statistics for all Vanderbilt University Breast Cancer SPORE projects, investigators and participants. Functions provided by this core include development of experimental designs, power analysis and sample size estimation, data acquisition and database development, statistical analysis and interpretation of findings, and collaboration on presentation of results. To achieve these functions, the core director and core biostatisticians are constantly available to investigators, and are in regular contact with the project and core leaders. The primary objectives of the Biostatistics Core are: 1. To provide study design and review all laboratory, animal and clinical studies including feasibility 2. To collaborate in project data analysis, interpretation of results, and the writing of final study 3. To provide relational database design, data entry, data tracking, forms, queries, and reports, and to 4. To work with Bioinformatics Core in the development of research project database, to maintain 5. To develop and evaluate statistical methods for experimental design and data analysis, assessment, power analysis and sample size estimation, reports and manuscripts, maintain computer databases for information storage and retrieval for all projects, data quality control and to ensure timely data capture. The Biostatistics Core support is required in all Breast Cancer SPORE studies. Core personnel have worked and will continue to work closely with project leaders to assure that the Core provides state-of- the-art statistical support.