1. 1College of Public Health, Zhengzhou University, Zhengzhou, Henan, China.
2. 2The State Key Laboratory of Esophageal Cancer Prevention & Treatment and The Key Laboratory of Tumor Epidemiology of Henan, Zhengzhou, Henan, China.
3. 3Xi'an Center for Disease Control and Prevention, Xi'an, Shaanxi, China.
4. 4School of Nursing and Health, Zhengzhou University, Zhengzhou, Henan, China.