1. Joint Committee for Nationwide Survey on Colorectal Liver Metastasis Bunkyo‐ku, Tokyo Japan
2. Department of Hepato‐Biliary‐Pancreatic and Breast Surgery Ehime University Graduate School of Medicine Toon Ehime Japan
3. Department of Surgery Yamaga City Medical Center Kumamoto Japan
4. Department of Surgery, Institute of Gastroenterology Tokyo Women's Medical University Shinjuku‐ku, Tokyo Japan
5. Department of Surgery Sano City Hospital Sano Tochigi Japan
6. Department of Surgery Utsunomiya Memorial Hospital Utsunomiya Tochigi Japan
7. Department of Surgery Tokyo Metropolitan Health and Hospitals Corporation Ohkubo Hospital Shinjuku‐ku, Tokyo Japan
8. Department of Gastroenterological Surgery Yokohama City University Graduate School of Medicine Yokohama Kanagawa Japan
9. Department of Surgery, Hepato‐Biliary‐Pancreatic Surgery Division, Graduate School of Medicine The University of Tokyo Bunkyo‐ku, Tokyo Japan
10. Department of Surgery Teikyo University School of Medicine Itabashi‐ku, Tokyo Japan
11. Department of Hepatobiliary and Pancreatic Surgery National Cancer Center Hospital East Kashiwa‐shi Chiba Japan
12. Department of Surgery Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku, Tokyo Japan
13. Department of Pediatrics Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku, Tokyo Japan
14. Department of Surgery Teikyo University Hospital Kawasaki Kanagawa Japan
15. Department of Gastrointestinal Chemotherapy Cancer Institute Hospital of Japanese Foundation for Cancer Research Koto‐ku, Tokyo Japan
16. Department of Biomedical Statistics and Bioinformatics Graduate School of Medicine, Kyoto University Sakyo‐ku, Kyoto Japan
17. International University of Health and Welfare Narita Hospital Minato‐ku, Tokyo Japan
18. Tokyo Medical and Dental University Bunkyo‐ku, Tokyo Japan