[1] Akita Univ Hosp, Div Esophageal Surg, Akita, Japan
[2] Akita Univ, Dept Thorac Surg, Grad Sch Med, Akita, Japan
[3] Japanese Red Cross Akita Hosp, Dept Gastroenterol Surg, Akita, Japan
[4] Akita Univ Hosp, Div Clin Pathol, Akita, Japan
[5] Akita Univ, Dept Thorac Surg, Grad Sch Med, 1-1-1 Hondo, Akita 0108543, Japan