1. Departments of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China
2. Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People's Republic of China
3. Department of Oncology, Section II, Jiangmen Central Hospital, Affiliated Jiangmen Hospital of Sun Yat-sen University, Jiangmen, People's Republic of China
4. Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, People's Republic of China
5. Department of Colorectal Surgery, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China