Affiliation: | 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 |