Notably, several retrospective studies have also examined the role of CXCR4 in NSCLC by investigating the association between CXCR4 expression with clinical outcome; NSCLC patients with greater CXCR4 expression on the surface of tumor cells have been observed to be more likely to have metastatic disease (12,13). The gene discussed is CXCR4; the disease is metastatic neoplasm.