1. Department of Radiotherapy; Tianjin Medical University Cancer Institute and Hospital; Tianjin 300060 P. R. China
2. National Clinical Research Center for Cancer; Tianjin Medical University Cancer Institute and Hospital; Tianjin 300060 P. R. China
3. Key Laboratory of Cancer Prevention and Therapy, Tianjin; Tianjin's Clinical Research Center for Cancer; Huanhu West Street Tianjin 300060 P. R. China
4. State Key Laboratory of Oncology in South China; Guangzhou 510060 Guangdong P. R. China
5. Sun Yat-sen University Cancer Center; Guangzhou 510060 Guangdong P. R. China