The Epidemiology of Basal Cell and Squamous Cell Carcinoma -- Histology of Epithelial Skin Tumors -- UV Damage and DNA Repair in Basal Cell and Squamous Cell Carcinomas -- Papillomavirus Infections and Cancerogenesis of Squamous Cell and Basal Cell Carcinomas -- The Immune System and Nonmelanoma Skin Cancers -- Cytogenetics of Basal Cell Carcinoma and Squamous Cell Carcinomas -- The Hedgehog Signaling Pathway and Epithelial Skin Cancer -- p53 Protein and Nonmelanoma Skin Cancer -- TGF-? Pathway and Cancerogenesis of Epithelial Skin Tumors -- PDGF Pathways and Growth of Basal Cell and Squamous Cell Carcinomas -- Apoptosis and Cancerogenesis of Basal Cell and Squamous Cell Carcinoma -- The Role of Telomerase for Cancerogenesis of Basal Cell and Squamous Cell Carcinomas. apid progress in the understanding of carcinogenesis and pathology of epitheUal skin cancer has led to new strategies for the prevention Rand treatment of these malignancies. The goal of this volume is to comprehensively cover in a highly readable overview our present knowledge of pathogenetic mechanisms and molecular biology of Basal Cell and Squamous Cell Carcinomas. Topics that are discussed in-depth by leading researchers and clinicians range from the newest findings in epidemiology, histology, photobiology, immunology, cytogenetics, and molecular pathology to new concepts for prophylaxis and treatment. Experts in the field as well as health care professionals not intimately involved in these specialized areas are provided with the most significant and timely information related to these topics. It is the aim of this book to summarize essential up-to-date information for clinicians and scientists interested in the biology of Basal Cell and Squamous Cell Carcinomas. The chapters are written by authors who are experts in their respective research areas, and I am gratefixl for their willingness to contribute to this book. I would also like to express my thanks to Ron Landes, Cynthia Conomos, Sara Lord and all the other members of the Landes Bioscience staff for their expertise, diligence and patience in helping me complete this work. Jorg Reichrathy Prof, Dn med. CHAPTER 1 The Epidemiology of Basal Cell and Squamous Cell Carcinoma Hao Wang and Thomas L.