[Cancer: three eras of personalized medicine].

Since the completion of the first human DNA sequence, genomic approaches have penetrated into cancer research and therapy: first through expression profiling for diagnostic, prognostic and predictive purposes, then by sequencing of tumour DNA in order to define and apply targeted therapies. These overlapping changes occurred quite rapidly and are now overshadowed by immuno-oncology approaches that show much promise. There is however still much left to understand to make this more widely applicable, and the extreme cost of these therapies is a serious concern.