This book reviews both genetic and biochemical data on the origin of genome instability and its impact on carcinogenesis. Reflecting recent discoveries and ongoing research, it discusses DNA repair mechanisms and hereditary cancer syndromes, as well as checkpoint mechanisms operating to safeguard chromosome integrity during cell cycle progression. Moreover, it summarises our current understanding of the various defects that may allow cancer cells to rapidly accumulate critical mutations and evolve, through processes reminiscent of Darwinian selection, an increasingly aggressive behaviour. Hopefully, this book will stimulate thought, discussion and experimentation, and serve as a rich source of information for a wide audience, including advanced students, researchers and clinical oncologists.