1. Department of SurgeryGastroenterological CenterYokohama City University Medical Center Yokohama Japan
2. Department of SurgeryYokosuka Kyosai Hospital Yokosuka Japan
3. Department of SurgeryNTT East Kanto Hospital Tokyo Japan
4. Department of Gastroenterological SurgeryGraduate School of MedicineYokohama City University Yokohama Japan