CEACAM5 and cancer: In addition, several potential circulating biomarkers have been identified: the carcinoembryonic antigen (CEA), cytokeratin-19 fragment (CYFRA21-1), neuron-specific enolase (NSE), cancer-associated antigens CA125 and CA19-9, and chromogranin A, together with molecular signatures as mutations in KRAS and TP53 genes.