Meanwhile, TAM may be suppressed in metastatic tumors, liver metastatic cells may preferentially reprogram macrophages and induce their specific functional states, and metastatic tumor cells in liver metastases preferentially express the ligand CD47 and thus may recruit or activate MRC1+ CCL18+ macrophages through the corresponding receptor SIRPA, suggesting that specific macrophage subpopulations may play a fundamental role in the formation of premetastatic niche in CLM (18). This evidence concerns the gene SIRPA and metastatic neoplasm.