A 54-year-old man presents with progressive dysphagia to solids for three months, in association with a sensation of food getting stuck in the middle of his chest. He has lost eight kilograms (17 pounds) in weight over the past three months. When closely questioned, he relates that he has experienced repeated episodes of regurgitant material coming up to his throat, especially at night, for several years now. His medical, surgical, and family histories are unremarkable. He is not on any medications—in particular, he has never taken medications for heartburn. He is an active smoker with a 30-pack-year smoking history. He only drinks socially.