1. Department of Gastrointestinal Surgery, Asan Medical Center, Seoul, Korea.
2. Department of Surgery, Seoul National University Bundang Hospital, Seongnam, Korea.
3. Department of Surgery, Chung-Ang University Gwangmyeong Hospital, Gwangmyeong, Korea.
4. Department of Surgery, St. Vincent’s Hospital, Suwon, Korea.
5. Department of Surgery, Seoul National University Hospital, Seoul, Korea.
6. Department of Surgery, Seoul National University College of Medicine, Seoul, Korea.