The Significance and Diagnostic Potential of CEA and FIB in Colorectal Cancer

ABSTRACT Background Colorectal cancer (CRC) is the third most common cancer worldwide; most cases are diagnosed at an advanced stage. This study explored the value of carcinoembryonic antigen (CEA) and fibrinogen (FIB) in the differential diagnosis of colorectal polyps and CRC. Methods Clinical data of 466 CRC patients and 231 patients with colorectal polyps treated at the Chinese PLA General Hospital from October 2021 to February 2024 were retrospectively analyzed. The efficacy of tumor markers in diagnosing CRC was assessed using receiver operating characteristic curves using the binary logistic regression model. Bioinformatics analysis of FIB‐related differentially expressed genes related to CRC was performed using the String, LinkedOmics, and Gene Expression Omnibus databases. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes signaling pathway enrichment analyses were performed using the Metascape database. Results The CRC group was older and had higher proportions of male patients, smokers, and drinkers than the colorectal polyp group ( p < 0.05). Compared with the colorectal polyp group, the CRC group had higher levels of CEA, carbohydrate antigen 19–9 (CA19‐9), cytokeratin 19 fragment (CYFRA21‐1), activated partial thromboplastin time (APTT), prothrombin time (PT), and FIB ( p < 0.01). CEA and FIB levels were significantly different between patients with different Tumor‐Node‐Metastasis staging ( p < 0.01). The combination of CEA and FIB showed better ability to discriminate CRC from colorectal polyps (sensitivity: 76.5%, specificity: 80.2%, area under the curve: 0.85). Protein‐protein interaction network analysis showed that the fibrinogen alpha (FGA) gene had the strongest correlation with albumin (ALB), alpha‐2‐Heremans Schmid glycoprotein (AHSG), and serpin peptidase inhibitor, clade D, member 1 (SERPIND1). Gene Ontology functional analysis in CRC showed that FGA and related genes were enriched in biological processes including biosynthesis of ribonucleoprotein complex and non‐coding ribonucleic acid metabolic process; in cellular components, they were primarily enriched in pre‐ribosomes; and in molecular functions, they were mainly enriched in binding of unfolded protein. Kyoto Encyclopedia of Genes and Genomes enrichment indicated that differential genes were mainly involved in pathways such as the Wnt signaling pathway. Conclusion The combination of CEA and FIB may be useful for the differential diagnosis of benign and malignant colorectal polyps and CRC and for monitoring disease progression.