1. Department of Gastroenterological and Pediatric Surgery; Oita University Faculty of Medicine; Yufu Japan
2. Department of Surgery; Kitasato University School of Medicine; Sagamihara Japan
3. Department of Surgery; Jichi Medical University Saitama Medical Center; Saitama Japan
4. JCOG Data Center, Multi-institutional Clinical Trial Support Center; National Cancer Center; Tokyo Japan
5. Oita University; Oita Japan