CEACAM5 and neoplasm: Objective. To compare the clinical value of serum microRNA21 (miR21) and other tumor markers in early diagnosis of non-small cell lung cancer (NSCLC). Methods. Serums carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA21-1), neuron-specific enolase (NSE), and miR21 were detected in 50 NSCLC cases and 60 healthy control individuals. Results. Average serums miR21, CEA, NSE, and CYFRA21-1 levels were significantly higher in the case group than in control group (P < 0.01).