The Southwest Oncology Group-led Prostate Cancer Prevention Trial (PCPT) was the first large-scale chemoprevention trial for prostate cancer (PCa). This trial, which enrolled >18,800 men, tested the ability of the 5-alpha-reductase inhibitor finasteride to reduce the period-prevalence of biopsy-proven PCa over a period of 7 years. A byproduct of the PCPT was the establishment of large specimen banks of biopsy tissue, prostatectomy specimens, serum, plasma, and white blood cells obtained from the participants at the end of the study and at various interim time points during the study. The overall aim of this revised application for Core C is to establish a Pathology and Genotyping Core in support of the molecular "Biology of the PCPT" Program Project. This core will provide expertise and resources in the following areas: 1) Archival Repository Management and Distribution of the various specimen banks established from the PCPT;2) Histopathology, including diagnostic interpretation, microtomy, microscopy, laser-capture microdissection (LCM), immunohistochemistry (IHC), and computer-assisted image analysis;and 3) Genotyping and hormone analysis, overseeing the isolation of DNA, genotyping of samples and hormone analysis to be carried out by specialized central facilities. This revised proposal addresses all of the comments from the review of the original proposal and adds new preliminary data regarding reliability and quantification of IHC, quantification of DNA extracted from serum, and extraction and amplification of DNA from paraffin-embedded tissue sections using LCM. Genotyping has also been streamlined to ensure sufficient DNA for the proposed studies and for future PCPT biology studies. Our intent is to provide the highest quality samples and pathological services to meet the needs of the research teams in the Program Project. It is our underlying hypothesis that the quality, reliability and applicability of translational research in PCa can only be guaranteed through the use of high-quality biological specimens that are handled, processed and interpreted in a uniform manner and that can be linked to clinical information and outcome.