This is a condition in which the lining of the lower esophagus (swallowing tube) just above the stomach has changed in its cellular make-up. The changes are due to damage from an excess of stomach acid that has refluxed upwards into the esophagus over a long period of time (see GERD, HIATUS HERNIA, ACID REFLUX). Usually, patients with BE have symptoms, but not always. The changed lining in and of itself is not cancer, but it can sometimes (rarely) be a precursor to cancer. The main approach to treating BE is to decrease the volume of acid that refluxes back into the esophagus to prevent further damage. BE is diagnosed at the time of an upper endoscopy exam, by both visual appearance and by biopsies (samples) which are obtained during the exam. If certain cellular changes (dysplasia) are found in the biopsy samples, further treatment may be required ( more aggressive acid suppressive medication, newer non-surgical technologies such as radiofrequency ablation or even surgery, with removal of the esophagus). Once a diagnosis of BE has been established, gastroenterologists usually repeat the endoscopic exam every few years to obtain samples from the changed lining and see if any evidence of dysplasia (cellular changes) has developed. Such a program of on-going endoscopic examination is referred to as ”surveillance”.