1. Department of General Thoracic Surgery, Saiseikai Yokohama-shi Tobu Hospital, Yokohama, Japan
2. Department of General Thoracic Surgery, Southern Tohoku General Hospital, Koriyama, Japan
3. Division of Chest Surgery, Department of Surgery, Showa University, Tokyo, Japan
4. Department of Thoracic Surgery, Shin-Yurigaoka General Hospital, Kawasaki, Japan