Colorectal cancer screenings are the most important factor in early detection. Most people should begin having a colonoscopy at age 50 at intervals of 10 years. In a colonoscopy, a tiny camera is used to examine the colon and rectum. If polyps are found, they can be removed during this procedure. A virtual colonoscopy uses a CT scan to create a 3D model of your colon and also reveals polyps or other problems. X-rays and blood tests may also be used to screen for colorectal cancer. Follow the links below to find WebMD's comprehensive coverage about how colorectal cancer develops, what it looks like, how to treat it, and much more.