Previous studies reported that higher CD8/eTreg ratio, PD-L1 combined positive score (CPS), tumor mutational burden (TMB), and CD8 + PD-1 + T cell infiltration predicted better response in pMMR tumors.13,22,23 This study discovered marvelously that patients aged <50 years and CEA level <5 ng/ml were independent predictive factors to pCR, while patients reached 100% pCR rate after meeting both conditions simultaneously. This evidence concerns the gene CEACAM5 and neoplasm.