[1] Natl Hosp Org Beppu Med Ctr, Dept Gen Thorac Surg, 1473 Uchikamado, Beppu, Oita 8740011, Japan
[2] Natl Hosp Org Shibukawa Med Ctr, Dept Chest Surg, Shibukawa, Japan
[3] Natl Hosp Org Kyushu Med Ctr, Dept Thorac Surg, Fukuoka, Japan
[4] Natl Hosp Org Hokkaido Canc Ctr, Dept Thorac Surg, Sapporo, Hokkaido, Japan
[5] Natl Hosp Org Nagasaki Med Ctr, Dept Thorac Surg, Omura, Japan
[6] Natl Hosp Org Kyushu Canc Ctr, Clin Res Inst, Canc Biostat Lab, Fukuoka, Japan