CEACAM5 and cancer: As common indicators of early pre-operative diagnosis and routine monitoring of post-operative follow-up of cancer, the prognostic values of serum CEA and CA19-9 for GC remain under investigation, and most previous studies only focus on the levels of tumour markers before surgery.21,22 In particular, there are few studies on the prognostic effects of post-operative CEA and CA19-9.