1. Department of Otolaryngology/Head and Neck Surgery, Jichi Medical University, Shimotsuke, Tochigi 329‑0498, Japan
2. Department of Otolaryngology/Head and Neck Surgery, Hamamatsu University School of Medicine, Hamamatsu 431‑3192, Japan
3. Division of Head and Neck, Cancer Institute, Japanese Foundation of Cancer Research, Tokyo 135‑8550, Japan
4. Department of Pathology, Cancer Institute, Japanese Foundation of Cancer Research, Tokyo 135‑8550, Japan
5. Department of Otolaryngology/Head and Neck Surgery, Jichi Medical University, Saitama Medical Center, Saitama 330‑8503, Japan
6. Department of Neurosurgery, Jichi Medical University, Saitama Medical Center, Saitama 330‑8503, Japan
7. Laboratory of Head and Neck Cancer Biology, Department of Otolaryngology/Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA