CEACAM5 and colorectal carcinoma: Currently, carcinoembryonic antigen (CEA) is commonly used in patients with CRC, alone or in combination with other biomarkers, such as cancer antigen 19.9 (CA19.9), cancer antigen 125 (CA125), cancer antigen 72–4 (CA72-4) and serum ferritin (SF) [13].