Conversely, blood‐based tumor markers, such as CEA, carbohydrate antigen 19‐9 (CA19‐9), carbohydrate antigen 72‐4 (CA72‐4), and carbohydrate antigen 125 (CA125) have been widely used in gastric cancer [12, 13, 14]. The gene discussed is CEACAM5; the disease is gastric cancer.