Although carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 19-9 have been widely used for auxiliary CRC diagnoses and prognostic predictions,9,10 previous studies have reported that CEA and CA19-9 present a diagnostic sensitivity of <50%.11,12 This means that more than half of the patients with CRC will be misdiagnosed based on CEA or CA19-9 alone. Here, CEACAM5 is linked to colorectal carcinoma.