CEACAM5 and cancer: CA, in the context of elevated serum CEA levels, differed from the other two histopathological types, showing unexpectedly higher risks for both overall survival (OS) (HR ═ 1.70, 95% CI ═ 1.65–1.75, P < 0.001) and cancer-specific survival (CSS) (HR ═ 1.78, 95% CI ═ 1.72–1.85, P < 0.001).