Microsatellite instability: a review of what the oncologist should know

Abstract

The patients with high microsatellite instability (MSI-H)/mismatch repair deficient (dMMR) tumors recently have been reported that can benefit from immunotherapy, and MSI can be used as a genetic instability of a tumor detection index. However, many studies have shown that there are many heterogeneous phenomena in patients with MSI tumors in terms of immunotherapy, prognosis and chemotherapy sensitivity. Here we mainly review the research results of MSI detection methods, the mechanisms of MSI occurrence and its relationship with related tumors, aiming to make a brief analysis of the current research status of MSI and provide comparable reference and guidance value for further research in this field.

Keywords: Cancer; MSI; MSI-H/dMMR; Microsatellite DNA.

Fig. 1

Lynch syndrome screening process. Lynch syndrome screening process. MMR immunohistochemical method is used to detect whether 4 MMR proteins of hMLH1, hPMS2, hMSH2 and hMSH6 are missing, and whether BRAF V600E mutation exists in hMLH1 negative protein and whether EpCAM mutation exists in hMLH1 positive protein, so as to determine whether there is MMR functional defect. MSI detection is to determine the stability of MSI sites by detecting nucleotide marker: two of the unstable loci were MSI-H, the instability of one of the loci was MSI-L, MSS was defined as the instability of zero loci. MMR mismatch repair, MSI-H microsatellite high instability, MSI-L microsatellite low instability, MSS microsatellite stability