The absolute value of CD4+ TSCM for the auxiliary diagnosis of CRC (pTNM stage I–IV), based on the AUC, was 0.758 (sensitivity: 0.612; specificity: 0.788), which was higher than that of CEA (AUC: 0.707) and CA199 (AUC: 0.552). Here, CEACAM5 is linked to colorectal carcinoma.