1. Department of Surgery and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Surgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
3. Department of Surgery, Chung-Ang University Gwangmyeong Hospital, Gwangmyeong, Korea.
4. Department of Surgery, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
5. Department of Surgery, Uijeongbu Eulji Medical Center, Eulji University, Uijeongbu, Korea.
6. Department of Surgery, Hallym University Dongtan Sacred Heart Hospital, Hwaseong, Korea.
7. Department of Surgery, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
8. Department of Surgery, Goodjang Hospital, Seoul, Korea.