Lung Cancer Laboratory Markers

The Lung Cancer Laboratory Markers panel is applied as part of a multimodal evaluation when lung cancer is suspected. It contributes supportive data for differentiating histologic categories (eg, small‑cell vs non–small‑cell lung cancer) and supplies adjunctive information relevant to staging in conjunction with imaging and pathology. This profile is also used to monitor therapeutic response following surgery, chemotherapy, or radiotherapy in patients who have elevated pretreatment marker levels, and to surveil for biochemical evidence of recurrence during follow‑up. Synonymous terms used clinically include laboratory markers for lung carcinoma and markers for malignant neoplasms of the lung.

Serologic markers used in lung cancer are largely glycoproteins or enzymes released by tumor cells or by adjacent nonmalignant tissues. Carcinoembryonic antigen (CEA) is an oncofetal glycoprotein that is often increased in adenocarcinomas, including a subset of non–small‑cell lung cancers. Numerous benign gastrointestinal, hepatic, and pulmonary conditions can also raise CEA; such elevations commonly fluctuate and return toward baseline as the benign process resolves, whereas malignant disease more often shows a progressive rise. Squamous cell carcinoma antigen (SCCA) is a 48‑kDa glycoprotein associated with squamous cell carcinomas, including a portion of lung cancers. Reported sensitivity is approximately 50%–60% with specificity near 80%. False‑positive increases may be seen in certain benign dermatologic or inflammatory disorders. Neuron‑specific enolase (NSE) is a glycolytic enzyme isoform enriched in neuroendocrine tissues. It is frequently elevated in small‑cell lung cancer and in other neuroendocrine neoplasms and is useful for differential assessment and for monitoring when pretreatment values are elevated. CA 19‑9 and CA 72‑4 are high–molecular‑weight glycoprotein antigens primarily linked to gastrointestinal and pancreaticobiliary malignancies, but levels can be increased in some lung cancers as well as in benign hepatic, pancreatic, gastrointestinal, and gynecologic conditions. Across this panel, individual markers are nonspecific and are intended to be interpreted as adjuncts to clinical evaluation, imaging, histopathology, and molecular studies rather than as standalone diagnostic tests.