CEACAM5 and gastric cancer: Serum HULC effectively differentiated primary GC patients from normal controls with an area under the ROC curves (AUC) of 0.888 (95% confidence interval [CI]: 0.843–0.934; P < 0.001) vs. 0.694 (95% CI: 0.621–0.767; P < 0.001) for CEA and 0.514 (95% CI: 0.433–0.595: P = 0.737) for CA72-4 (Figure 3C).