CXCL12 and esophageal squamous cell carcinoma: The positive CXCL12 expression was significantly correlated with lymph node metastasis, tumor stage, and lymphatic invasion [15], whereas the CXCR4 expression was significantly higher in the ESCC patients with lymph node metastasis and T3 stage of tumor than in group without lymph node metastasis and patients with T1-T2 stages [15–18].