CEACAM5 and breast cancer: Accordingly, CEA is applied to aid the diagnosis, determine the prognosis, monitor recurrence, and evaluate the therapeutic efficacy in cancer patients.160 In patients with breast cancer, CEA is one of the most frequently used biomarkers in the diagnosis, prognosis, and prediction of survival for different breast cancer molecular subtypes.161 In CRC patients, CEA level is a meaningful prognostic and diagnostic biomarker.