The application of serum protein biomarkers, i.e., CEA and CA 19–9, as biomarker for clinical CRC management has been intensively studied but found to lack sufficient sensitivity and specificity.38 While CEA performed particularly well in our study with regard to CRC staging when applying absolute values, even below the cut-off, the use of the accepted cut-off (5 ng/mL) diminished the power of CEA for staging considerably: Only 37.5% of patients with a systemic disease (UICC IV) showed CEA values above cut-off levels. The gene discussed is CEACAM5; the disease is colorectal carcinoma.