1 Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Guangdong Esophageal Cancer Research Institute, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
2 Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Guangdong Esophageal Cancer Research Institute, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China. Electronic address: [email protected].