1. Department of Gastroenterology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
2. Department of Radiation Oncology, Kochi University, Kochi 783-8505, Japan
3. Department of Radiation Oncology, Hiroshima University, Hiroshima 734-8551, Japan
4. Department of Gastroenterology, Hiroshima Prefectural Hospital, Hiroshima 734-0004, Japan