Polyps Colon polyps are tiny growths that form on the inside the colon. Polyps are very common and half of all adults have them. They do not usually cause symptoms and are usually found during a colonoscopy. Most polyps are usually not dangerous, but some can contain early cancer and it is often not possible to tell you this unless you have them removed during a colonoscopy and have it examined by an expert (pathologist) under a microscope. Please see the bowel cancer screening section for more information.