The expression level of Lipocalin-2 in serum of patients with poorly differentiated lung cancer was higher than that of patients with well differentiated lung cancer; the expression level of Lipocalin-2 in serum of patients with lymph node metastasis was higher than that of patients without lymph node metastasis; the expression level of Lipocalin-2 in patients with clinical stage III + IV lung cancer was significantly higher than that of patients with clinical stage I + II lung cancer, and the differences were statistically significant (P < 0.05). The gene discussed is LCN2; the disease is lung cancer.