Clinical medicine is in the midst of a revolution that is being driven by an increasing understanding of the human genome and advances in molecular biotechnology. This revolution promises to transform clinical practice from population-based risk assessment and empirical treatment to a predictive, individualized model based on the molecular classification of disease and targeted therapy. The expectation is, of course, that personalized approaches to clinical care will increase the efficacy of treatment while decreasing its toxicity and cost.Nowhere is this transformation more apparent than in oncology. Cancer is a complex disease. Our current taxonomy of cancers, which is based . . .