1. Department of Gastroenterology and Endoscopy, National Cancer Center Hospital East, Kashiwa, Japan;
2. Endoscopy Division, National Cancer Center Hospital, Tokyo, Japan;
3. Department of Gastrointestinal Oncology, Osaka International Cancer Institute, Osaka, Japan;
4. Department of Gastroenterology, Ishikawa Prefectural Central Hospital, Ishikawa, Japan;
5. Department of Gastroenterology, Kitasato University School of Medicine, Kanagawa, Japan;
6. Department of Therapeutic Oncology, Kyoto University Graduate School of Medicine, Kyoto, Japan;
7. Clinical Research Support Office, National Cancer Center Hospital East, Kashiwa, Japan;
8. Biostatistics Division, Center for Research Administration and Support, National Cancer Center Hospital East, Kashiwa, Japan.