1. Department of Epidemiology and Statistics, College of Public Health, Zhengzhou University, Zhengzhou, China
2. Henan Key Laboratory of Tumor Epidemiology, Zhengzhou University, Zhengzhou, China
3. State Key Laboratory of Esophageal Cancer Prevention & Treatment, Zhengzhou University, Zhengzhou, China
4. Department of Teaching and Research, Third Affiliated Hospital of Zhengzhou University, Zhengzhou, China