ENO2 and lung carcinoma: Previous studies have confirmed that serum levels of tumor markers such as neuron‐specific enolase (NSE), carcinoembryonic antigen (CEA), cytokeratin 19 fragments (CYFRA21‐1), carbohydrate antigen 125 (CA125)and carbohydrate antigen 153 (CA153) are significantly higher in lung cancer patients than in patients with benign lung lesions and healthy individuals, and the levels are significantly higher in patients with postoperative recurrence than in patients without recurrence [7, 8].