CEACAM5 and colorectal carcinoma: Moreover, protein biomarkers such as CA19-9, CA 72-4 and carcinoembryonic antigen (CEA), can be used as PRBs of colorectal carcinoma (Zheng et al., 2001), and plasma vascular endothelial growth factor-A (VEGF-A) can be used as a PRBs for colon cancer (Luo and Xu, 2014).