A colonoscopy is the best way to diagnose colon cancer, but it’s so inconvenient and unpleasant that less than 25 percent of the at-risk population ever have one. The main alternative, a test for traces of blood in a stool sample, generates a high percentage of false positives. So Giovanni Traverso, a staff researcher at John Hopkins University’s Kimmel Cancer Center, set out to develop a convenient gene-based stool test that would reliably detect colon cancer at its earliest stages- when it’s still curable. Traverso had to develop sophisticated methods for isolating minute amounts of relevant DNA from feces samples patients collect at home, as well as a novel means of finding cancer-causing mutations in the DNA. In an early study, the test generated no false positives, but it didn’t detect all cancers. Traverso and colleagues are working to automate the test and boost its sensitivity; he’s also about to resume medical school in England. With luck, as a doctor, he’ll be able to get patients to take a colon cancer tests that could save lives.