CEACAM5 and gastric cancer: To estimate the ability of the three tumour markers to distinguish GC from benign gastric disease, ROC curves were generated, and the results showed that the area under the curve (AUC) values for CEA, CA199, and CA 125 were 0.727(0.681–0.773), 0.594(0.54–0.648), and 0.566(0.513–0.618), respectively, with optimal cut-off values of 1.95 ng/ml, 17.12 U/ml, 9.675 U/ml (Fig. 1a, Table 2).