1. Department of Gastroenterology Dokkyo Medical University Tochigi Japan
2. Department of Gastroenterology Southern‐Tohoku General Hospital Fukushima Japan
3. Department of Gastroenterology Utsunomiya Memorial Hospital Tochigi Japan
4. Department of Minimally Invasive Surgical and Medical Oncology Fukushima Medical University Fukushima Japan
5. Department of Diagnostic Pathology Dokkyo Medical University Tochigi Japan