The changes in the expression levels of carcinoembryonic antigen (CEA) mRNA, serum collagen type VI type alpha 3 chain (COL6A3) and alpha-1,4 acetylglucosaminyltransferase (α4GnT) mRNA were closely linked to the cancer of pancreas and about 33% of the patients with pancreatic carcinoma and 22% patients with gastric cancer were positive for CEA mRNA in the peripheral blood samples (Sayeed et al., 2020). Here, CEACAM5 is linked to gastric cancer.