For the last decade cancer research has been guided by a common vision of how a single cell, outcompeting its neighbors, evolves into a malignant tumor. Through a series of random mutations, genes that encourage cellular division are pushed into overdrive, while genes that normally send growth-restraining signals are taken offline. With the accelerator floored and the brake lines cut, the cell and its progeny are free to rapidly multiply. More mutations accumulate, allowing the cancer cells to elude other safeguards and to invade neighboring tissue and metastasize. These basic principles — laid out 11 years ago in a landmark...