With ELISAs to test serum CEA (encoded by CEACAM5), CK8 (encoded by KRT8), CK18 (encoded by KRT18), CK20 (encoded by KRT20), MUC13 and EPCAM in CRC, CA patients and healthy controls, the results showed that CEA, CK18 and CK20 were significantly higher in CRC and CA patients than in healthy controls (all P < 0.05) (Figure 1C). This evidence concerns the gene CEACAM5 and cancer.