Polymorphisms of Thymidylate Synthase Gene and Correlation of Its Protein Expression to Lymph Node Metastasis of Esophageal Squamous Cell Carcinoma是什么意思 Polymorphisms of Thymidylate Synthase Gene and Correlation of Its Protein Expression to Lymph Node Metastasis of Esophageal Squamous Cell Carcinoma怎么读