1 Nikko Kinen Hospital, Department of Otorhinolaryngology, Hokkaido, Japan; Asahikawa Medical University, Department of Otolaryngology-Head and Neck Surgery, Hokkaido, Japan.
2 Asahikawa Medical University, Department of Otolaryngology-Head and Neck Surgery, Hokkaido, Japan; Asahikawa Medical University, Department of Innovative Head & Neck Cancer Research and Treatment (IHNCRT), Hokkaido, Japan. Electronic address: t-kumai@asahikawa-med.ac.jp.
3 Nikko Kinen Hospital, Department of Otorhinolaryngology, Hokkaido, Japan.