1. Department of Oral & Maxillofacial Surgery, University of Tokyo Hospital, Tokyo, Japan
2. Division for Health Service Promotion, University of Tokyo, Tokyo, Japan
3. Department of Pathology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
4. Department of Oral Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
5. Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
6. Department of Gastrointestinal Surgery, Peking University Cancer Hospital & Institute, Beijing, China