1. Department of Gastroenterology Sapporo City General Hospital Sapporo Japan
2. Department of Clinical Laboratories Sapporo City General Hospital Sapporo Japan
3. Department of Pathology Sapporo City General Hospital Sapporo Japan
4. Department of Surgery Sapporo City General Hospital Sapporo Japan
5. Department of Biostatistics, Graduate School of Medicine Hokkaido University Sapporo Japan