MRC1 and neoplasm: Although this patient obtained the opportunity of radical resection after 6 cycles of neoadjuvant anti-PD-1 monotherapy, both the preoperative imaging and postoperative pathological results suggested poor tumor regression, and the patient was the only case with TRG of grade 3 in this study.Therefore, the efficacy of immunotherapy may be reduced when the MMR protein expression and MSI status are inconsistent.