CEACAM5 and gastric cancer: Carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9) are commonly used markers for gastric cancer.9 Although both markers are often measured in patients with gastric cancer preoperatively, the clinical correlation between CEA and CA 19-9 is reported as unclear and controversial.10-12 In addition to these common used markers; carbohydrate antigen 125 (CA 125) and carbohydrate antigen 72-4 (CA 72-4) have been reported to be elevated in advanced gastric cancer.13