Tumor cell-derived CCL2 is known to be critical for the recruitment and infiltration of monocytes and TAMs in several tumor types, including ESCC, CRC, HCC, and breast cancer.571,572 Accumulating evidence have suggested that both CCL2 and its CCR2 receptor are implicated in both the inflammation and progression of tumors. This evidence concerns the gene CCL2 and esophageal squamous cell carcinoma.