As a single biomarker, CEA demonstrated the highest sensitivities for all CRC stages, 17.6% for stages 0 and I combined, 51.4% for stage II, 68.0% for stage III, 72.4% for stage IV, and 55.7% for all CRCs with a specificity of 100.0% (Figure 3 and Supplementary Table 2). Here, CEACAM5 is linked to colorectal carcinoma.