Colon cancer can be cured if it and pre-cancerous polyps are caught early. But doctors at Mayo Clinic say only half of all people at risk of colon cancer get screened for the disease. That's because some people don't know they should be screened and others simply don't want to undergo colonoscopy. But a new test developed at Mayo Clinic makes the screening process a whole lot easier. It's called virtual colonoscopy or CT colonography.