The purpose of this book is to provide an up to date review of the nature and consequences of epigenetic changes in cancer. Epigenetics literally means “above” genetics, and consists of heritable gene expression or other phenotypic states not accounted for by DNA base sequence. Epigenetic changes are now known to make a large contribution to various aspects of tumorigenesis. These changes include alterations in global and promoter specific DNA methylation, activating and repressive histone modifications, and changes in higher order chromatin structures. Each of these topics will be covered in this book.