[1] Aichi Canc Ctr Hosp, Dept Head & Neck Surg, Nagoya, Aichi, Japan
[2] Hokkaido Univ, Fac Med, Dept Med Oncol, Sapporo, Hokkaido, Japan
[3] Hokkaido Univ, Grad Sch Med, Sapporo, Hokkaido, Japan
[4] Okayama Univ Hosp, Dept Otolaryngol Head & Neck Surg, Okayama, Japan
[5] Kyushu Univ, Grad Sch Med Sci, Dept Otolaryngol, Fukuoka, Japan
[6] Shizuoka Canc Ctr, Div Gastrointestinal Oncol, Nagaizumi, Shizuoka, Japan
[7] Osaka Int Canc Inst, Dept Head & Neck Surg, Osaka, Japan
[8] Tokyo Med Univ, Dept Otorhinolaryngol Head & Neck Surg, Tokyo, Japan
[9] Univ Tokyo Hosp, Otorhinolaryngol & Head & Neck Surg, Tokyo, Japan
[10] Int Univ Hlth & Welf, Mita Hosp, Head & Neck Oncol Ctr, Tokyo, Japan
[11] Hiroshima Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Hiroshima, Japan
[12] Univ Ryukyu Hosp, Dept Otorhinolaryngol Head & Neck Surg, Nishihara, Okinawa, Japan
[13] Japanese Fdn Canc Res, Dept Med Oncol, Canc Inst Hosp, Tokyo, Japan
[14] Kurume Univ Hosp, Dept Otolaryngol Head & Neck Surg, Kurume, Fukuoka, Japan
[15] Yokohama City Univ Med, Dept Otolaryngol Head & Neck Surg, Yokohama, Kanagawa, Japan
[16] Saga Univ Hosp, Dept Otolaryngol Head & Neck Surg, Saga, Japan
[17] Keiyukai Sapporo Hosp, Dept Otolaryngol Head & Neck Surg, Sapporo, Hokkaido, Japan
[18] Kyoto Univ Hosp, Dept Otolaryngol Head & Neck Surg, Kyoto, Japan
[19] Miyagi Canc Ctr, Div Head & Neck Canc Oncol, Sendai, Miyagi, Japan
[20] Natl Hosp Org Shikoku Canc Ctr, Dept Head & Neck Surg, Matsuyama, Ehime, Japan
[21] Hirosaki Univ, Dept Otorhinolaryngol, Grad Sch Med, Hirosaki, Aomori, Japan
[22] Chiba Univ Hosp, Dept Med Oncol, Chiba, Japan
[23] Chiba Univ Hosp, Dept Otorhinolaryngol Head & Neck Surg, Chiba, Japan
[24] Tokyo Med & Dent Univ Med Hosp, Dept Head & Neck Surg, Tokyo, Japan
[25] ONO Pharmaceut Co Ltd, Med Affairs, Osaka, Japan
[26] Bristol Myers Squibb KK, Japan Med & Dev, Tokyo, Japan
[27] Hokkaido Univ, Dept Otolaryngol Head & Neck Surg, Fac Med, Kita Ku, Kita15 Nishi7, Sapporo, Hokkaido 0608638, Japan
[28] Hokkaido Univ, Grad Sch Med, Kita Ku, Kita15 Nishi7, Sapporo, Hokkaido 0608638, Japan