CEACAM5 and neoplasm: Univariate analysis revealed that tumor diameter ≥ 5.0 cm, cN2, MRF positivity before treatment, CEA before treatment ≥ 5.0 ng/ml, CEA after chemoradiation ≥ 5.0 ng/ml, CEA after one cycle of CAPOX ≥ 5.0 ng/ml, CEA after 2 cycles of CAPOX ≥ 5.0 ng/ml and CEA clearance pattern Group B after chemoradiation were risk factors for poor regression response.