1. Joint Committee for Nationwide Survey on Colorectal Liver Metastasis Tokyo Japan
2. Department of Gastroenterological Surgery Yokohama City University Graduate School of Medicine Yokohama Kanagawa Japan
3. Department of Hepato‐Biliary‐Pancreatic and Breast Surgery Ehime University Graduate School of Medicine Toon Ehime Japan
4. Department of Gastroenterological Surgery New Tokyo Hospital Matsudo Chiba Japan
5. Department of Surgery Yamaga City Medical Center Yamaga Kumamoto Japan
6. Department of Surgery Sano City Hospital Sano Tochigi Japan
7. Department of Surgery Institute of Gastroenterology Tokyo Women’s Medical University Shinjuku‐ku Tokyo Japan
8. Department of Surgery Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku Tokyo Japan
9. Hepato‐Biliary‐Pancreatic Surgery Division Department of Surgery Graduate School of Medicine 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 Pediatrics Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku Tokyo Japan
13. Department of Surgery Teikyo University Hospital, Mizonokuchi Kawasaki Kanagawa Japan
14. Department of Gastroenterological Chemotherapy Cancer Institute Hospital of Japanese Foundation for Cancer Research Koto‐ku Tokyo Japan
15. Department of Biomedical Statistics and Bioinformatics Graduate School of Medicine Kyoto University Shogoin Sakyo‐ku Japan
16. International University of Health and Welfare Mita Hospital Minato‐ku Tokyo Japan
17. Tokyo Medical and Dental University Bunkyo‐ku Tokyo Japan