CEACAM5 and lung cancer: Biomarkers for lung cancer were as follows: cytokeratin 19 fragment antigen 21 − 1 (CYFRA21-1) = 5.06 ng/ml (reference < 3.30 ng/ml), carcinoembryonic antigen (CEA) = 1.5 ng/ml (reference < 5.0 ng/ml), and neuron-specific enolase (NSE) = 14.4 ng/ml (reference < 18.3 ng/ml).