Barrett's esophagus is a disorder in which the lining of the esophagus is damaged by stomach acid and changed to a lining similar to that of the stomach. When you eat, food passes from your throat to your stomach through the esophagus. Once food is in the stomach, a ring of muscles keeps it from leaking backward into the esophagus. If these muscles do not close tightly, stomach acid can leak back into the esophagus. This is called reflux or gastroesophageal reflux. Patients with Barrett's esophagus may develop more changes in the esophagus called dysplasia. When dysplasia is present, the risk of getting cancer of the esophagus increases. While looking at the esophagus with an endoscope, a gastroenterologist may perform biopsies in different parts of the esophagus. These biopsies help diagnose Barrett's esophagus, and look for changes that could lead to cancer.