[1] Chiba Univ, Grad Sch Med, Dept Respirol, Chiba 2608670, Japan
[2] Chiba Univ, Grad Sch Med, Dept Esophageal Gastro Intestinal Surg, Chiba 2608670, Japan
[3] Chiba Univ, Grad Sch Med, Dept Gen Thorac Surg, Chiba 2608670, Japan
[4] Chiba Univ, Grad Sch Med, Dept Respirol, 1 Inohana Chuo Ku, Chiba 2608670, Japan