TP53 and endometrial cancer: 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].