The combination of these four miRNAs and CEA showed an AUC of 0.976, a sensitivity of 94.3%, and a specificity of 90.5% to distinguish NSCLC from gastric cancer (P < 0.0001; 95% CI: 0.927–0.996; S3 Fig and S4 Table). The gene discussed is CEACAM5; the disease is gastric cancer.