Most cancers in the colon originate in adenoma type polyps. These adenomas start out being benign. Then, as they get larger, they can become cancerous. That is why polyps are always removed from the colon when they are found. Cancers come in all sizes. Image 1 shows a small cancerous polyp about the size of an olive. The chance for a complete cure in this case is probably very good. Image 2 shows the same site after the polyp has been removed with cautery. The base of the polyp looks nice and clean. Images 3 and 4 show more advanced cancers in the rectum and cecum or right colon respectively. At this point, surgery is needed to remove the diseased segment of colon.