Cancer is a leading cause of death worldwide and the total number of cases globally keeps increasing. For many years, cancer has been thought to be caused by a series of DNA sequence alterations and thus is thought to be a "genetic" disease. However, studies in the last decade, including the large-scale cancer genomics projects, have highlighted the rising importance of epigenetic regulation in cancer. Here, we review recent advances in understanding how chromatin-based epigenetic regulation participates in tumorigenesis and discuss the growing implications of these advances for developing novel strategies to prevent, diagnose, as well as treat cancer.