Carcinoembryonic antigen (CEA), cytokeratin fragment 19 (CYFRA21-1), neuron-specific enolase (NSE), and SCC antigen are among the most well-known serum tumor biomarkers for NSCLC, and they have been mainly regarded as predictive or prognostic biomarkers in NSCLC patients. The gene discussed is CEACAM5; the disease is neoplasm.