The esophagus is the hollow tube that leads from the throat (pharynx) to the stomach. Food does not just fall through the esophagus into the stomach. The walls of the esophagus propel food to the stomach by rhythmic waves of muscular contractions called peristalsis.When the esophagus is not in use, these sphincters close so that food and stomach acid do not flow back up the esophagus from the stomach to the mouth. During swallowing, the sphincters open so food can pass to the stomach. The most common problem with the esophagus is GERD (gastroesophageal reflux disease). With GERD, a muscle at the end of your esophagus does not close properly. Infectious esophagitis is rare and can be due to bacteria, viruses, fungi, or parasites. You are at increased risk for this type of esophagitis if you have a weakened immune system due to disease or medications. Other problems include heartburn, cancer, and eosinophilic esophagitis. Doctors may use various tests to make a diagnosis. These include imaging tests, an upper endoscopy, and a biopsy. Treatment depends on the problem. Some problems get better with over-the-counter medicines or changes in diet. Others may need prescription medicines or surgery. Esophageal cancer is the sixth most common cause of cancer deaths worldwide. Incidence rates vary within different geographic locations. In some regions, higher rates of esophageal cancer may be attributed to tobacco and alcohol use or particular nutritional habits and obesity.