1. Department of Otorhinolaryngology, Head and Neck Surgery Graduate School of Medicine Chiba University Chiba Japan
2. Department of Molecular Oncology Graduate School of Medicine Chiba University Chiba Japan
3. Department of Pathology Chiba University Hospital Chiba Japan
4. Department of Otolaryngology/Head and Neck Surgery Hamamatsu University School of Medicine Chiba Japan
5. Japan Organization of Occupational Health and Safety Chiba Rosai Hospital Chiba Japan