1. Division of Proton Therapy, Radiation and Proton Therapy Center, Shizuoka Cancer Center Hospital , 1007 Shimonagakubo, Nagaizumi-cho, Suntou-gun, Shizuoka 411-8777 , Japan
2. The Japanese Society for Radiation Oncology, Particle Therapy Division, Colorectal Cancer Working Group
3. QST Hospital, National Institutes for Quantum Science and Technology , 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555 , Japan
4. Department of Radiation Oncology & Proton Medical Research Center , Faculty of Medicine, , 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 , Japan
5. University of Tsukuba , Faculty of Medicine, , 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575 , Japan
6. Department of Radiation Oncology, Hokkaido University Faculty of Medicine , Kita 15, Nishi 7, Kita-ku, Sapporo, Hokkaido 060-8638 , Japan
7. Department of Radiology, Kyoto Prefectural University of Medicine , 465 Kajiicho, Kamigyo-ku, Kyoto 602-0841 , Japan
8. Department of Radiology, Osaka Heavy Ion Therapy Center , 3-1-10 Otemae, Chuo-ku, Osaka-city, Osaka 540-0008 , Japan
9. Department of Radiology , Division of Radiation Oncology, , 2-2-2, Iidanishi, Yamagata city, Yamagata 990-9585 , Japan
10. Yamagata University Faculty of Medicine , Division of Radiation Oncology, , 2-2-2, Iidanishi, Yamagata city, Yamagata 990-9585 , Japan
11. Division of Radiation Oncology, Radiation and Proton Therapy Center, Shizuoka Cancer Center Hospital , 1007 Shimonagakubo, Nagaizumi-cho, Suntou-gun, Shizuoka 411-8777 , Japan
12. Clinical Research Support Center, Shizuoka Cancer Center Hospital , 1007 Shimonagakubo, Nagaizumi-cho, Suntou-gun, Shizuoka 411-8777 , Japan
13. Department of Surgical Oncology, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 , Japan
14. Department of Surgery, National Defense Medical College , 3-2 Namiki, Tokorozawa, Saitama 359-8513 , Japan
15. Department of Carbon Ion Radiotherapy , Graduate School of Medicine, , 3-1-10, Otemae, Chuo-ku, Osaka City, Osaka 540-0008 , Japan
16. Osaka University , Graduate School of Medicine, , 3-1-10, Otemae, Chuo-ku, Osaka City, Osaka 540-0008 , Japan