CEACAM5 and gastric cancer: Among 166 propensity matched gastric cancer patients with normal preoperative serum CEA levels, multivariate analysis demonstrated that pStage (HR: 7.803, 95% CI: 3.015–24.041; p <  0.001) and PNI (HR: 3.078, 95% CI: 1.232–8.707; p = 0.016) were identified as independent prognostic factors of CSS.