Oro-pharyngeal cancers can develop from squamous dysplastic precursor lesions, which occur in a subset of common white (leukoplakia), red (erythroplasia), or mixed oro-pharyngeal plaques. Known risk factors for oro-pharyngeal cancer include tobacco smoke, alcohol consumption, diet and, in a subset of tumors, human papillomavirus (HPV). Along the oro-pharyngeal disease continuum, there may be variations in gene expression precursor lesions as a result of exposure to smoking, alcohol and HPV. However, the components of gene expression that are most likely associated with tumorigenesis in these tissues are poorly understood. This study will focus upon early gene expression profiles in the oral cavity and oropharynx in subjects who have precursor lesions and have been exposed to the common risk factors for carcinoma development including smoking and HPV infection. This application is to conduct pilot testing and establish appropriate procedures for an international prospective cohort study of the natural history of oro-pharyngeal cancer precursors among men and women at high risk of oro-pharyngeal cancer at Montefiore Medical Center, Bronx-NY. Brush biopsy specimens will be used to collect a transepithelial sample of cells from oro-pharyngeal plaques, as well as normal tissue from defined regions of the oral and pharyngeal mucosa. Measurement of gene expression will employ novel high-throughput cDNA microarray analysis and PCR-based HPV DNA testing. Oro-pharyngeal dysplasia will be diagnosed using cytopathology. Under this application, we will assess our planned instruments and procedures on an initial sample of 40 subjects. This planning period will allow for precise identification of methodologies, standardization of instruments and assays to be utilized by additional participating centers in a subsequent application.