The most comprehensive study to date of how lung cancer evolves in response to selection pressures indicates the genetic profile at diagnosis can be used to predict how a tumor is likely to progress, opening up new prospects for personalized medicine and potential therapeutic targets. The data were generated in Tracerx (Tracking cancer evolution through therapy), a £14 million (US$17.4 million) study funded by the charity Cancer Research UK (CRUK) with the aim of defining how clonal heterogeneity of tumor cells affects the risk of recurrence and survival.