The study of epigenetic mechanisms in cancer, such as DNA methylation and histone modifications, has revealed a plethora of events that contribute to cancer through stable changes in the expression of genes critical to transformation pathways. In this mini review we look at the different epigenetic modifications prevalent in this neoplastic phenotype, focusing on breast cancer. Most encouragingly, research in epigenetics has led to improved survival of patients with certain forms of lymphoma and leukemia through the use of drugs that alter DNA methylation and histone acetylation. Thus, we look at the clinical utility of targeting epigenetic pathways. In addition, we explore numerous other clinical applications of epigenetics, in areas such as cancer screening and early detection, prevention, classification for epidemiology and prognostic purposes, and predicting outcomes after standard therapy. © 2012 Elsevier Ireland Ltd.