Mammographic breast density is a strong predictor of breast cancer risk. At this present time, little is known[unreadable] about which attribute(s) of mammographic density also contributes to breast cancer risk. To gain insight[unreadable] into this question this Program Project Grant seeks to use human tissue to explore the biologic connection[unreadable] between mammographic density and molecular markers for breast cancer risk. To accomplish these goals,[unreadable] the Core will provide services that are fundamental to all projects within the Program Project Grant[unreadable] application.[unreadable] The primary goals of the Tissue and Biostatistics Core are to process breast tissue for study by the[unreadable] Program Project Investigators and provide high quality characterization and biostatistical analysis of[unreadable] samples. Core personnel will process fresh tissue from donors in a systematic manner, which will allow[unreadable] correlation of tissue blocks with density images for Projects 1 and 2. The Core will coordinate routine tissue[unreadable] processing, embedding, sectioning and staining through the UCSF Comprehensive Cancer Center Tissue[unreadable] Core. Routine immunohistochemistry stains for Projects 2 and 3 will be coordinated though the UCSF[unreadable] Comprehensive Cancer Center Immunohistochemistry and Molecular Pathology Core. Core pathologists[unreadable] will be responsible for the interpretation of H&E sections and immunohistochemistry stains. The Core[unreadable] biostatistician will be involved in study design and statistical analyses of data obtained by Projects 1, 2, 3,[unreadable] and 4.