Preclinical data have confirmed that the serum concentrations of CEA in patients with advanced non-small-cell lung cancer (NSCLC) were correlated with the occurrence of brain metastases (58), and high CEA expression was associated with clinicopathological characteristics in lung cancer patients, including lymph node metastasis and vascular infiltration (59). This evidence concerns the gene CEACAM5 and metastatic malignant neoplasm in the lymph nodes.