Cross-Sectional Study to Establish the Utility of Serum Tumor Markers in the Diagnosis of Lung Cancer

BACKGROUND: Reliable blood markers for aiding lung cancer (LC) diagnosis and differentiating LC from tuberculosis are lacking in India. METHODOLOGY: In this single-centre, cross-sectional, real-world study, serum levels of 5 TMs (CEA, CYFRA 21-1, SCC, ProGRP, NSE) were measured from consented patients with suspicious lung nodules who were candidates for biopsy, and also from healthy controls. TM level measurement was done through electrochemiluminescent immunoassay, followed by histological diagnosis on the biopsied specimen. Using package insert cut-offs, sensitivity and specificity of the 5 TMs were evaluated individually and in combination. Using receiver operating characteristic (ROC) curves of individual TMs, the ability of CEA, CYFRA 21-1, and ProGRP taken together was evaluated for its ability to differentiate LC from no-LC. RESULTS: Out of 178 subjects, 160 had LC (147 NSCLC; 13 SCLC). NSCLC patients had higher median values of CYFRA 21-1 and SCC; SCLC patients had higher median values of CEA, NSE, and ProGRP. Adenocarcinoma-NSCLC patients had higher median values of CEA, CYFRA 21-1, NSE, and ProGRP; squamous-NSCLC patients had higher median value of SCC. For differentiating LC from no-LC, the combination of all 5 TMs (sensitivity:97.5%, specificity:33.3%) and combination of CEA, CYFRA 21-1 and ProGRP (sensitivity:91.3%, specificity:88.9%) were found suitable. CONCLUSION: Combination of all 5 TMs, and combination of CEA, CYFRA 21-1, and ProGRP represents an easy and non-invasive method for aid in LC diagnosis that does not require technical expertise. TM evaluation can also supplement histological diagnosis of LC.