1. Key Laboratory of Cancer Prevention and Therapy, Department of Esophageal Cancer, National Clinical Research Center for Cancer, Tianjin Medical University Cancer Institute and Hospital, Tianjin 300070, P.R. China
2. Department of Obstetrics and Gynecology, Tianjin Medical University General Hospital, Tianjin 300070, P.R. China
3. Department of Thoracic Surgery, The Fourth Affiliated Hospital, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China