In some cases, an endoscopy procedure can be used to treat the disease. For instance, if polyps are found in the duodenum, they can be taken out. Polyps are abnormal growths of the GI lining. Polyps start out as non-cancerous tumors. However, some types of polyps can grow to become malignant. If you have a polyp, your doctor will take it out and send it to be tested under a microscope to determine its type.