ENO2 and lung cancer: Squamous cell carcinoma antigen (SCC), cytokeratin 19 fragment (Cyfra21-1), neuron-specific enolase (NSE), and carcinoembryonic antigen (CEA) are widely used for screening, early detection, monitoring therapy efficacy, and defining prognosis of lung cancer [10, 11]; however, several studies have also shown that serum tumor marker levels are elevated in patients with chronic kidney disease (CKD) [12–15].