CEACAM5 and lung carcinoma: At the time, the initial pulmonary mass was visualized on imaging, and all tumor markers for primary lung carcinoma, namely, carcinoembryonic antigen (CEA), sialyl LewisX, squamous cell carcinoma-related antigen, cytokeratin 19 fragment, neuron-specific enolase, and pro-gastrin-releasing peptide, were negative.