After comparing data on tumor biomarkers in lung cancer patients with and without mediastinal lymph node metastasis, we found that the concentrations of AFP, CEA, and CYFRA 21-1 were significantly higher in patients with mediastinal lymph node metastasis, while HB was higher in patients without mediastinal lymph node metastasis (p < 0.05) (Table 2). Here, CEACAM5 is linked to metastatic malignant neoplasm in the lymph nodes.