Concordance assessment for results of identification of microsatellite instability and deficiency in enzyme for repair for unpaired bases by PCR and IHC methods in colorectal cancer

Therapy choice for colorectal cancer is currently quite extensive and depends on molecular subtype of the tumor, since it has a high level of intertumor molecular heterogeneity. Microsatellite instability (MSI) is one of the important predictors of response to checkpoint inhibitors of immune response. At the moment, the defects in the unpaired base repair system (dMMR) and MSI are recognized using 2 methods: immunohistochemical and polymerase chain reaction. The present work investigated the concordance between these methods in a large sample of patients with colorectal cancer and assessed the reasons for discrepancies in the results.

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