Universal Molecular Testing for Endometrial Cancers: Institutional Experience and Focus on Phenotypic and Clinical Characterization of POLE-mutated Cases.

Our institution began universal molecular testing for newly diagnosed endometrial cancers in April 2023.

Of 198 tested endometrial cancers, 40.9% (n=81) had no specific molecular profile, 33.8% (n=67) were p53 abnormal, 19.7% (n=39) were MMRd, and 5.6% (n=11) had POLE exonuclease domain/proofreading mutations associated with the ultramutated phenotype.

At least one aggressive histopathologic feature was seen in 5/10 POLEmut cases that had resection specimens.

TP53 variants were present in 5/11 POLE specimens and were often subclonal.