1. Department of Otolaryngology‐Head and Neck SurgeryHokuto HospitalObihiro Hokkaido Japan
2. Department of Biology and Genetics, Laboratory of Cancer Medical ScienceHokuto HospitalObihiro Hokkaido Japan
3. Department of NeurosurgeryHokuto HospitalObihiro Hokkaido Japan
4. Department of Otolaryngology‐Head and Neck SurgeryAsahikawa Medical UniversityAsahikawa Hokkaido Japan
5. Department of PathologyHokkaido University Graduate School of MedicineSapporo Hokkaido Japan