1. Department of Epidemiology and StatisticsQiqihar Medical University Qiqihar Heilongjiang China
2. Duke Cancer Institute, Duke University Medical Center Durham NC
3. Department of Population Health SciencesDuke University School of Medicine Durham NC
4. Department of Community and Family MedicineDuke University Medical Center Durham NC
5. Department of Biostatistics and BioinformaticsDuke University School of Medicine Durham NC
6. Department of SurgeryDuke University School of Medicine Durham NC
7. Department of MedicineDuke University School of Medicine Durham NC