Introduction/Background*Microsatellite instability (MSI) is routinely analyzed in patients with endometrial cancers for selecting patients for immunotherapy. Standard reference methods recommended for MSI/dMMR (deficient MisMatch Repair) are immunohistochemistry and pentaplex PCR assays.

Methodology We evaluated here the performance of a custom capture-based NGS method, digital droplet (dd)-PCR and automated-PCR for the determination of MSI status in 30 formalin-fixed paraffin embedded (FFPE) tissue samples from patients with endometrial and colorectal cancers. All samples have been previously characterized using standard reference methods, set as gold standard.

Result(s)*Overall agreement, sensitivity and specificity were 93.3%, 93.8% and 92.9% for NGS. Overall agreement, sensitivity and specificity were 100% for dd-PCR and automated-PCR assays.

Conclusion*NGS, dd-PCR and automated-PCR can be used routinely used for the analysis of MSI detection and represent complementary options to IHC and pentaplex PCR assays. Dd-PCR and automated-PCR assays allow easy and fast analysis while NGS allows simultaneous analysis of MSI and clinically relevant genomic alterations.