A malignant growth of cells in the esophagus. There are two major variants: epidermoid (squamous) carcinoma and adenocarcinoma. This is an uncommon cancer in the United States though it is relatively common in Iran, France, Switzerland with highest mortality rates seen in China, Singapore, and Puerto Rico. Excessive ethanol and cigarette usage increases the risk for development of this cancer, acting in a synergistic fashion. (DeVita et al. Cancer. p.776-778 4th edition Lippincott)