1. Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hospital, Key Laboratory of Cancer Prevention and Therapy, National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Tianjin 300060, P.R. China
2. Department of Chemoradiotherapy, North China University of Science and Technology Affiliated Hospital, Tangshan, Hebei 063000, P.R. China
3. Department of Chemoradiotherapy, Tangshan People's Hospital, Tangshan, Hebei 063000, P.R. China