ENO2 and metastatic malignant neoplasm in the lymph nodes: In these patients, we observed a correlation between increased levels of CEA and occurrence of mediastinal and peritoneal metastasis (P < 0.05) (Additional file 4: Table S4A); between increased levels of CYFRA21-1 and liver metastasis (P < 0.05) (Additional file 4: Table S4B); and between increased NSE levels and occurrence of lymph node metastasis (Negative: 42.1%; moderate: 60.1%; high: 77.8%;P < 0.05) (Additional file 4: Table S4C).