Colorectal cancer (cancer of the colon [large intestine] or rectum) is a common cause of cancer death in the United States. Experts recommend that people 50 years of age and older get colon cancer screening. Most cancer of the colon begins as polyps, which are benign (noncancerous) growths on the colon's inner surface. Removing a polyp prevents it from ever becoming cancer. There are different kinds of polyps, some that are likely to become cancer and some that rarely do. Doctors can remove polyps during colonoscopy. Colonoscopy is a procedure during which doctors examine the inside of the colon with a flexible, lighted instrument. After removing a polyp, doctors often repeat the colonoscopy periodically to look for new polyps or cancer.