In early-stage NSCLC, the ROC curves showed miR-182, miR-183, miR-210, and CEA with AUCs of 0.826, 0.660, 0.699, and 0.706; sensitivities of 66.7%, 73.6%, 66.7%, and 83.9%; and specificities of 90.5%, 66.7%, 71.4%, and 57.1%, respectively, to distinguish NSCLC from gastric cancer (P < 0.0001, = 0.0150, 0.0009, and 0.0016; 95% CI: 0.741–0.892, 0.562–0.748, 0.603–0.783, and 0.611–0.790, respectively; S3 Fig). Here, CEACAM5 is linked to gastric cancer.