Microsatellite instability is biased in Amsterdam II-defined Lynch-related cancer cases with family history but is rare in other cancers: a summary of 1000 analyses

Microsatellite instability (MSI) is a key marker for predicting the response of immune checkpoint inhibitors (ICIs) and for screening Lynch syndrome (LS). This study aimed to see the characteristics of cancers with high level of MSI (MSI-H) in genetic medicine and precision medicine. This study analyzed the incidence of MSI-H in 1000 cancers and compared according to several clinical and demographic factors. The incidence of MSI-H was highest in endometrial cancers (26.7%, 20/75), followed by small intestine (20%, 3/15) and colorectal cancers (CRCs)(13.7%, 64/466); the sum of these three cancers (15.6%) was significantly higher than that of other types (2.5%)(P