Only nine cases (8.0% of our cohort) represented feasible candidates as possible true WT1-negative HGSOC (advanced stage at diagnosis and TP53m without mutations suggestive of endometrioid carcinoma i.e., MMR, PTEN, CTNNB1, PIK3CA, ARID1A and KRAS wild-type), which are recognised as a rare phenomenon (≤5% HGSOC cases)24. This evidence concerns the gene MRC1 and endometrioid adenocarcinoma.