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?

- 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.