POLE and endometrial cancer: Pathogenic somatic mutations in the exonuclease domain of the replicative DNA polymerase epsilon (POLE) define a subgroup of endometrial cancers (ECs) with ultramutation (frequently ≥ 100 mutations/Mb), characteristic mutation signature (COSMIC signature 10) 1, enhanced immune response 2, 3, and excellent clinical outcome 4, 5, 6, 7.