1. Japan North-East Thoracic Surgical Study Group (JNETS), Sendai, Japan
2. Division of Endoscopy, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
3. Department of Surgery 2, Faculty of Medicine, Yamagata University, Yamagata, Japan
4. Department of Chest Surgery, Fukushima Medical University, Fukushima, Japan
5. Division of Thoracic Surgery, Kanazawa Medical University, Uchinada, Ishikawa, Japan
6. Department of Thoracic Surgery, Tohoku University Hospital, Sendai, Japan
7. Department of General Thoracic Surgery, Dokkyo Medical University, Mibu, Tochigi, Japan
8. Department of Thoracic Surgery, Yamagata Prefectural Central Hospital, Yamagata, Japan
9. Department of Thoracic Surgery, Miyagi Cancer Center, Natori, Miyagi, Japan
10. Department of Thoracic Surgery, Sendai Medical Center, Sendai, Japan
11. Department of General Thoracic Surgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan
12. Department of Thoracic Surgery, Aomori Prefectural Central Hospital, Aomori, Japan
13. Department of Thoracic Surgery, Iwate Prefectural Isawa Hospital, Mizusawa, Iwate, Japan
14. Department of General Thoracic Surgery, Iwate Medical University, Morioka, Iwate, Japan