Several factors contribute to the development of esophageal cancer. Alcohol and tobacco consumption are the greatest causative factors for squamous cell esophageal cancer. Dietary factors also play an important role in the development of esophageal cancer. Vitamin A, iron, and riboflavin deficiency have been implicated as causes of this form of cancer. The lack of a varied, balanced diet also appears to be contributory. Medical conditions are associated with an increased risk of esophageal cancer include tylosis (a rare autosomal-dominant disorder), longstanding untreated achalasia, prior mediastinal irradiation, Barrett's esophagus, and chronic reflux esophagitis.