Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute and Harvard School of Public Health, Boston, MA 02115, USA Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA 02215, USA Division of Molecular and Cellular Oncology, Department of Medical Oncology, Dana-Farber Cancer Institute Department of Medicine, Brigham and Womens Hospital and Harvard Medical School, Boston, MA 02115, USA.