MSI testing is crucial for several reasons. Firstly, it helps in the diagnosis and classification of certain cancers, particularly those associated with Lynch syndrome, a hereditary condition that increases the risk of several types of cancer. Secondly, MSI status can influence treatment decisions. For instance, tumors with high microsatellite instability (MSI-H) are more likely to respond to immunotherapy, particularly with immune checkpoint inhibitors like pembrolizumab. Lastly, MSI testing can have prognostic implications, as MSI-H tumors often have a different clinical outcome compared to microsatellite stable (MSS) tumors.
