The widespread use of serum markers during cancer screenings has led to the belief that there may be tumor markers yet to be discovered that offer better specificity and sensitivity than prostate-specific antigen (PSA). Proteomics, the analysis and characterization of global protein modifications, will add to our understanding of gene function and aid in biomarker and/or therapeutic target discovery. In the past, most proteomic studies were either performed using tumor cell lines or homogenized bulk tissue. Unfortunately, these approaches may not accurately reflect molecular events that take place in the actual ductal epithelium that change as a consequence of the malignant process. This report describes alternative proteomic-based approaches aimed at the identification of protein markers in the actual premalignant and frankly malignant epithelium.