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 pathol­ ogy 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.