1. Department of Oncology; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea
2. Department of Clinical Epidemiology and Biostatistics; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea
3. Department of Gastroenterology; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea
4. Department of Surgery; University of Ulsan College of Medicine, Asan Medical Center; Seoul Korea