1. Department of Radiation Oncology Sun Yat‐sen University Cancer Center State Key Laboratory of Oncology in South China Collaborative Innovation Center for Cancer Medicine Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy Guangzhou People's Republic of China
2. Ji'an Central People's Hospital Ji'an People's Republic of China
3. Department of Medical Statistics and Epidemiology School of Public Health Sun Yat‐sen University Guangzhou China