Although the efficacy of various blood-based biomarkers (e.g., squamous cell carcinoma antigen [SCC-Ag], carcinoembryonic antigen [CEA] and cytokeratin-19 fragment [CYFRA21-1]) have been examined, none of these biomarkers are adequate as stand-alone ESCC diagnostic biomarkers [5, 6]. The gene discussed is CEACAM5; the disease is esophageal squamous cell carcinoma.