1. Multidisciplinary Treatment Cancer Center, Kurume University Hospital, Kurume 830-0011, Japan
2. Department of Surgery, Kurume University School of Medicine, Kurume 830-0011, Japan
3. Division of Gastroenterology, Department of Medicine, Kurume University School of Medicine, Kurume 830-0011, Japan
4. Biostatistics Center, Kurume University, Kurume 830-0011, Japan