 1.1 Esophageal squamous cell carcinoma Esophageal cancer is the seventh most common cancer in Korea, with almost 400,000 new patients diagnosed annually worldwide. There are large variations in the predominant histological type throughout the world but the majority of worldwide esophageal cancers are squamous cell carcinoma arising from the upper and middle thirds of the esophagus. Esophageal cancer is a highly virulent disease with a five-year survival rate of 10-15 . Metastatic esophageal carcinoma is an incurable disease with median survival duration of 6 to 8 months . 