1. Department of Clinical Oncology, Graduate School of Medicine, Akita University, Akita, Japan
2. Department of Colorectal Surgery, Tokyo Metropolitan Cancer and Infectious Disease Center Komagome Hospital, Tokyo, Japan
3. Department of Gastroenterology & Neurology, Graduate School of Medicine, Akita University, Akita, Japan
4. Department of Pathology, Akita University Hospital, Akita, Japan