[1] Hokkaido Univ, Grad Sch Dent Med, Dept Oral Pathobiol Sci, Sapporo, Hokkaido 060, Japan
[2] Natl Canc Ctr Hosp E, Div Head & Neck Surg, Chiba, Japan
[3] Shizuoka Canc Ctr Hosp, Div Head & Neck Surg, Shizuoka, Japan
[4] Shizuoka Canc Ctr Hosp, Div Plast & Reconstruct Surg, Shizuoka, Japan
[5] Shizuoka Canc Hosp, Div Oral Surg, Shizuoka, Japan