MRC1 and neoplasm: In addition, because of the low concordance between dMMR and MSI-H in many extraintestinal tumors, when we use the MSI assay as a routine concomitant diagnostic test for pan-tumor immunotherapy, we should refer to both MMR and PDL1IHC assessment and TMB assay results to avoid missing the treatment timing due to the presence of an MSS state in the absence of MMR protein expression.