Consistency analysis of mismatch repair protein expression and microsatellite stability in colorectal cancer

Objective To investigate the consistency between mismatch repair proyeins expressions detected by immunohistochemistry (IHC) and microsatellite instability(MSI) identified by next-generation sequencing (NGS), and evaluate the correlation of these results with the clinical characteristics of Chinese colorectal cancer (CRC). Methods Using IHC and NGS to identify mismatch repair (MMR) and MSI status in CRC, and assessing the consistency between these different detection methods. Results The concordance rate of MSI status detected by IHC and NGS was 98.36%, indicating good agreement (Kappa=0.856). Certain pathogenic or likely pathogenic germline variants were present in the pMMR/MSI-H subtype. The co-deficiency of MLH1 and PMS2 was most common in the dMMR/MSS subtype. Patients with inconsistent typing were more likely to have early-onset right-sided colon cancer (P