Epigenetic alterations can be heritable and stable, but also dynamic. This plasticity has raised the question of whether epigenetic changes can be drivers of tumorigenesis. Aryee et al. analysed genome-wide methylation profiles in metastatic prostate cancer using 'cityscape' plots. Although they found inter-individual heterogeneity among patients, methylation alterations in the primary tumour and metastases were similar in each individual. In general, hypermethylated regions were enriched for cancer-related genes. These results suggest that DNA methylation might be a selectable driver event.