1. Department of Gastroenterology Endoscopy Division, National Cancer Center Hospital East, Kashiwa, Japan
2. Pathology Division, Research Center for Innovative Oncology, National Cancer Center, Kashiwa, Japan
3. Division of Radiation Oncology, National Cancer Center Hospital East, Kashiwa, Japan
4. Department of Head and Neck Surgery, National Cancer Center Hospital East, Kashiwa, Japan