1. Department of Gastroenterology, Tianjin Nankai Hospital, Tianjin 300100, P.R. China
2. Department of Gastroenterology, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
3. Department of Oncology, Hebei Provincial Hospital of Traditional Chinese Medicine, Shijiazhuang, Hebei 050011, P.R. China