7. Has "alarm features" in symptomatology, including odynophagia, severe dysphagia, bleeding, weight loss, anemia, and blood in stool, pointing to a possible malignant disease of the gastrointestinal (GI) tract. Participants displaying "alarm symptoms" in addition to the "typical" gastroesophageal reflux disease (GERD) symptoms may be included based on endoscopic exclusion of malignancy.