1. Department of Radiation Oncology, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan
2. Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan
3. Department of Head and Neck Oncology, National Cancer Center Hospital, 5-1-1, Tsukiji Chuo-ku, Tokyo, Japan
4. Head and Neck Medical Oncology Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan
5. Department of Oral Health and Diagnostic Sciences, National Cancer Center Hospital, 5-1-1, Tsukiji Chuo-ku, Tokyo, Japan