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, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
4. Department of Surgery, Chung-Ang University Gwangmyeong Hospital, Gwangmyeong, Korea.