1. Japan Clinical Oncology Group Data Center/Operations Office, National Cancer Center Hospital , Tokyo 104-0045 , Japan
2. Cancer Treatment Center, Kansai Medical University Hospital , Osaka 573-1191 , Japan
3. Department of Hepatobiliary and Pancreatic Oncology, National Cancer Center Hospital , Tokyo 104-0045 , Japan
4. Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University , Kyoto 606-8507 , Japan
5. Department of Radiation Oncology, Showa University School of Medicine , Tokyo 142-8666 , Japan
6. Department of Gastroenterology, Kanagawa Cancer Center , Yokohama 241-8515 , Japan
7. Department of Gastroenterology, Cancer Institute Hospital , Tokyo 135-8550 , Japan