<prompt> A 54-year-old man with a long history of indigestion after meals and heaburn presents with upper abdominal pain. He was treated with proton-pump inhibitors for gastroesophageal reflux 3 years . An endoscopic biopsy of the lower esophagus shows glandular metaplasia. The patient described is at increased risk of developing which of the following diseases of the esophagus?AchalasiaAdenocarcinomaCandidiasisPlummer-Vinson syndrome  <response>: - Barrett esophagus carries a serious risk of malignant transformation to adenocarcinoma, risk correlates with length of involved esophagus degree of dysplasia. - Viually all esophageal adenocarcinomas arise in the background of metaplastic epithelium of Barrett esophagus. - Symptoms clinical course of adenocarcinoma of esophagus are similar to squamous cell carcinoma which include dysphagia, pain, occasionally bleeding. 