1 Department of Thoracic Surgery, Fudan University Shanghai Cancer Center, Shanghai, People's Republic of China.
2 Department of Epidemiology, School of Public Health and The Key Laboratory of Public Health Safety of Ministry of Education, Fudan University, Shanghai, People's Republic of China.
3 Department of Thoracic Surgery, Fudan University Shanghai Cancer Center, Shanghai, People's Republic of China. Electronic address: hqchen1@yahoo.com.