1. Division of Foregut Surgery, Korea University College of Medicine, Seoul
2. Division of Foregut Surgery, Korea University Anam Hospital, Seoul
3. Department of Surgery, Ajou University School of Medicine, Suwon
4. Department of Surgery, Korea University Ansan Hospital, Ansan
5. Department of Surgery, Keimyung University Dongsan Medical Centre, Daegu
6. Department of Surgery, Chonnam National University Medical School, Jeollanam-do
7. Department of Surgery, Catholic University of Seoul St Mary’s Hospital, Seoul, Republic of Korea
8. Department of Surgery, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea
9. Department of Surgery, Eulji University Hospital, Daejeon
10. Department of Surgery, Busan Paik Hospital, Inje University
11. Department of Surgery, Jeju National University School of Medicine, Jeju
12. Department of Surgery, Soonchunhyang University Hospital Cheonan, Cheonan
13. Department of Surgery, Incheon St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul
14. Department of Surgery, Asan Medical Centre, University of Ulsan College of Medicine, Seoul
15. Department of Surgery, Haeundae Paik Hospital, Inje University College of Medicine, Busan
16. Department of Surgery, Daejeon St. Mary’s Hospital, College of Medicine, The Catholic University of Korea
17. Department of Surgery, Kyung Hee University Hospital at Gangdong, Seoul
18. Department of Internal Medicine, Korea University College of Medicine, Seoul
19. Department of Biostatistics, Korea University College of Medicine, Seoul