Molecular Profiling of H-MSI/dMMR/for Endometrial Cancer Patients: “New Challenges in Diagnostic Routine Practice”

Endometrial cancer (EC) represents one of the most newly diagnosed cancers across gynecological malignancies. In particular, a plethora of risk factors (both biological and lifestyle-related) drastically impact the incidence rate of novel diagnosis accounting for 8300 cases/year. In the recent era of precision medicine EC molecular classification, integrating ESGO/ESTRO/ESP guidelines, four distinct diagnostic groups have been established including POLE-mutant (POLE-pos); High-instability MSI (H-MSI)–MMR-deficient (MMR-d); p53-abnormal (p53abn); and non-specific molecular profile (NSMP), also known as p53-wild-type EC patients on the basis of clinically relevant emerging biomarkers. In addition, molecular testing also plays a pivotal role in defining the best therapeutical option. In this scenario, the European Society for Medical Oncology (ESMO) recommended d-MMR/MSI-H status evaluation in the diagnostic workflow of Lynch syndrome or selecting EC patients that could benefit from immune checkpoint inhibitors (ICIs). Although immunohistochemistry (IHC) is considered the gold standard approach for d-MMR profiling, a series of molecular PCR-based techniques have rapidly developed to integrate H-MSI status in routine practice. Here, we technically overviewed the most relevant commercially available diagnostic assays for the determination of the H-MSI/dMMR status in EC patients.