1. Department of Surgery, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.
2. Department of Surgery, Daerim St. Mary's Hospital, Seoul, Korea.
3. Department of Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
4. Department of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
5. Department of Surgery, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, Korea.
6. Department of Surgery, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
7. Department of Surgery, Korea University Guro Hospital, Seoul, Korea.
8. Department of Surgery, Myongji Hospital, Seonam University College of Medicine, Goyang, Korea.
9. Department of Surgery, Chungbuk National University College of Medicine, Cheongju, Korea.
10. Department of Surgery, Gyeongsang National University Changwon Hospital, Gyeongsang National University School of Medicine, Changwon, Korea.
11. Department of Surgery, Dankook University College of Medicine, Cheonan, Korea.
12. Department of Surgery, International St. Mary's Hospital, Catholic Kwandong University, Incheon, Korea.