Various circulating protein biomarkers, including carbohydrate antigen 125 (CA125), CA19-9, carcinoembryonic (CEA), alpha fetoprotein (AFP), and ferritin, are applied for monitoring and diagnosing CRC in the clinic; however, these biomarkers only achieved 10.39–46.59% sensitivity and 80~95% specificity in diagnosing CRC [5,6]. Here, CEACAM5 is linked to colorectal carcinoma.