This book offers an overview of the epidemiology and primary prevention for most forms of human cancer. It summarizes concepts and methods of epidemiology, the biology of cancer, cancer genetics, and the emerging potential of biomarkers. It also reviews specific cancer sites in a consistent way, providing clinical and pathological outlines, descriptive epidemiology, and a comprehensive account of traditional and molecular risk factors and their etiological importance. To facilitate reading and use of our Textbook as a reference, we have consistently addressed potential risk factors in the same order throughout all site-specific chapters. Acknowledging that any causal inference has an element of subjectivity, we have also attempted to classify the strength of existing evidence into distinct categories for each cancer site. An epilogue summarizes the major contributions that epidemiology has made in the last few decades to our understanding of the causes of cancer, and speculates about future developments.