We aimed to confirm (1) if CNPY2 isoform 2 is detectable in peripheral blood, both in CRC patients and healthy control subjects; (2) if there are differences in the serum levels of CNPY2 isoform 2 between CRC patients and healthy controls; (3) if it is feasible to apply CNPY2 isoform 2 measurements for the early detection of CRC; and (4) if the combination of CNPY2 isoform 2, CEA and CA19-9 results in an improved efficacy for CRC diagnosis. Here, CEACAM5 is linked to colorectal carcinoma.