In preparation for minor surgery, John Leventhal needed a routine chest x-ray.When the New Haven, CT, doctor joined the radiologist who was examining the film, he was shocked by what he saw: an opaque blotch deep in his lung. "As a physician," says Leventhal, "you're taught in medical school that when you see a mass like that, it means lung cancer." Leventhal's medical training also taught him that to confirm the diagnosis, his doctors would need to crack open his rib cage to get a piece of the suspect tissue that would be closely examined by a pathologist-an extremely painful and hazardous operation. The weekend before that surgery, Leventhal went off on a family ski vacation. He recalls thinking, "This is the last time I will go skiing for a long, long time."

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