Dong Tian1,2,3, Jun Nakajima4. 1. Department of Thoracic Surgery, The University of Tokyo Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan. 2. Department of Thoracic Surgery, Affiliated Hospital of North Sichuan Medical College, Nanchong, China. 3. Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, China. 4. Department of Thoracic Surgery, The University of Tokyo Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan. nakajima-tho@h.u-tokyo.ac.jp.