Rectal bleeding could be a powerful early warning sign of colon cancer among younger adults, a new study says. Such bleeding increased more than eightfold the odds of a colon cancer diagnosis among people younger than 50, researchers reported Tuesday at the American College of Surgeons' annual meeting in Chicago. By comparison, a family history of colon cancer was tied to just a twofold increase in risk, researchers found. About 70% of the patients diagnosed had no family history of colon