“…The Proactive Molecular Risk Classifier for Endometrial Cancer introduced four subgroups of EC: (1) DNA polymerase epsilon, catalytic subunit ( POLE )-mutant subgroup, harboring mutations in the exonuclease domain in exons 9–14; (2) MMRd subgroup, showing the loss of expression for one or more MMR proteins; (3) p53-abnormal subgroup, demonstrating aberrant p53 expression pattern indicating pathogenic TP53 mutation; and (4) no specific molecular profile (NSMP) subgroup [ 63 , 64 , 65 ]. Even though the vast majority of NSMP ECs is low-grade endometrioid carcinoma, the NSMP subgroup also encompasses high-grade EC, clear cell carcinoma, undifferentiated carcinoma, carcinosarcoma, and MLA [ 36 , 40 , 50 , 51 , 53 , 57 , 65 , 66 , 67 , 68 ]. In this study, the majority of MLA cases harbored activating KRAS mutations but not POLE -mutant signatures, MMR deficiency, or TP53 mutation; confirming that these cases belong to the NSMP subgroup.…”