Background: To investigate the value of carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA21-1), squamous cell carcinoma antigen (SCC-Ag), and gastrin-releasing peptide (pro-GRP) in the differential diagnosis of lung cancer.
Methods:We enrolled 120 patients with malignant lung cancer who were treated at our hospital between June 2018 to June 2020. A further 58 patients with benign lung tumors and 60 healthy volunteers were also enrolled. Serum levels of CEA, CYFRA21-1, SCC-Ag, and pro-GRP were determined and compared across different populations, different pathological types, and different TNM stages. An ROC curve was drawn to evaluate the value of the four indicators when combined for the diagnosis of lung cancer.Results: The levels of CEA, CYFRA21-1, SCC-Ag, and pro-GRP in the malignant group were significantly higher than those in the benign and healthy groups (P<0.05). CEA in adenocarcinoma was significantly higher than that in squamous cell carcinoma (SCC) and small cell carcinoma (P>0.05), and CYFRA21-1 in non-small cell carcinoma was significantly higher than that in small cell carcinoma (P<0.05).Pro-GRP in small cell carcinoma was significantly higher than that in non-small cell carcinoma (P<0.05), and the SCC-Ag level in SCC was significantly higher than that in small cell carcinoma and adenocarcinoma (P<0.05). There was no statistically significant difference in CEA among various pathological types (P>0.05).However, there were significant differences in the levels of CEA and pro-GRP in different TMN stages (P<0.05), and in the levels of CEA and pro-GRP in different TMN stages (P<0.05) where from stage I to stage IV CEA, pro -GRP levels increased. There was a significant difference in CYFRA21-1 levels in stages I-III (P<0.05), and in stages III and IV, although there was no statistically significant difference in SCC-Ag in different stages (P>0.05). The area under the curve (AUC) for the combined diagnosis of lung cancer with the four markers was 0.9250 (95% CI: 0.8866-0.9634), the sensitivity was 93.29%, and the specificity was 84.32%.Conclusions: Joint inspection of CEA, CYFRA21-1, SCC-Ag, and pro-GRP levels has certain clinical value for the differential diagnosis of lung cancer.