However, it cannot diagnose cancer at early stage and its usage is restricted in clinic for the invasive procedure.[3] In the present, several serum cancer biomarkers have been used in clinic, such as carcinoembryonic antigen (CEA), carbohydrate antigens 125 (CA 125), α-fetoprotein (AFP), and so on.[4–7] Nevertheless, these markers are minimally useful for early cancer screening for their relatively low sensitivity and specificity. Here, CEACAM5 is linked to cancer.