1. Department of Colon and Rectal Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
2. Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
4. Biomedical Research Institute, Seoul National University Hospital, Seoul, Korea.