After the September 11 attacks, Congress became worried that terrorists targeting the U.S. might explode a radiological weapon—most likely a “dirty” bomb, a kind of weapon that relies on a conventional explosive to spread radioactive materials packed around it. In 2004 Congress funded several research centers to create drugs to protect survivors and first responders from radiation injury. But the biggest beneficiary of this research might be a much different and far larger group of people: cancer patients.