53 percent -- That's how much the death rate from colorectal cancer was cut among people who had colonoscopies during which precancerous growths, known as adenomatous polyps, were removed. The New England Journal of Medicine reported that patients in a study were tracked for 20 years, and their death rate from colorectal cancer was compared with that of the general population. So coverage of preventive care, including colonoscopies, clearly has the potential to save lives. But only if you have the exam.