Cancer epigenome profiling such as DNA methylation (5mC) and DNA hydroxymethylation (5hmC) is emerging as a sensitive approach for cancer detection and risk stratification. 5mC modification has been widely described in many cancer types including prostate cancer; however, the 5hmC landscape is yet to be explored. In this issue of Cancer Research, Sjöström and colleagues have comprehensively incorporated genomic, transcriptomic, and epigenomic, including 5hmC, data to interrogate the molecular evolution of prostate cancer. See related article by Sjöström et al., p. 3888.