1. Department of Thoracic Surgery, JA Hiroshima General Hospital , 1-3-3 Jigozen, Hatsukaichi, Hiroshima 738-8503 , Japan
2. Department of Respiratory Medicine, JA Hiroshima General Hospital , 1-3-3 Jigozen, Hatsukaichi, Hiroshima 738-8503 , Japan
3. Department of Pathology, JA Hiroshima General Hospital , 1-3-3 Jigozen, Hatsukaichi, Hiroshima 738-8503 , Japan