Most people can avoid the need for invasive colorectal cancer screening tests, such as colonoscopy, by following a regimen of annual stool-based tests, according to a study by the University of Washington School of Public Health and Group Health Research Institute. Researchers found that after a decade of annual fecal occult blood tests (FOBTs), only 23 percent of people had one false-positive result or more; most of those went on to have a colonoscopy. The rate of false positives per screening was 4.4 percent. Researchers examined more than 181,000 test results from more than 94,000 individuals at Group Health, an integrated healthcare system in Washington State. Patients were 50 to 79 years old and the tests were conducted between 1997 and 2009.