1. Department of Otorhinolaryngology, Head and Neck Surgery, Tokyo Medical University, Tokyo, Japan;
2. Department of Otolaryngology, Head and Neck Surgery, Tokyo Medical University Hachioji Medical Center, Hachioji, Japan;
3. Department of Clinical Oncology, Tokyo Medical University Hachioji Medical Center, Hachioji, Japan;
4. Department of Head and Neck Oncology and Surgery, International University of Health and Welfare Mita Hospital, Tokyo, Japan;
5. Department of Otorhinolaryngology, Head and Neck Surgery, Kitasato University School of Medicine, Kanagawa, Japan;
6. Department of Head and Neck Surgery, National Cancer Center Hospital, Tokyo, Japan