1. Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 739-8526, Japan
2. Department of Advanced Medicine, Hiroshima University, Hiroshima 739-8526, Japan
3. Department of Gastroenterology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 739-8526, Japan
4. Department of Anatomical Pathology, Hiroshima University, Hiroshima 739-8526, Japan