Clinicopathological Features and Risk Stratification of Multiple-Classifier Endometrial Cancers: A Multicenter Study...

Rationale: The ProMisE molecular classification improves risk assessment in endometrial cancer (EC), but 3-11% of cases exhibit overlapping molecular features, complicating clinical decisions. We analyzed the prevalence and clinicopathological profiles of multiple-classifier ECs in a large Polish cohort. Methods: In this retrospective study (2022-2025), 1075 ECs from four institutions were classified by MMR and p53 immunohistochemistry and POLE exon sequencing. Tumors showing ≥2 molecular features (e.g., MMRd-p53abn, POLEmut-p53abn) were categorized as multiple-classifier ECs. Results: Multiple-classifier ECs comprised 6.9% (74/1075), with MMRd-p53abn (3.9%) being most common. These tumors exhibited more aggressive features vs. MMRd-only: G3 (28.57% vs. 11.79%, p = 0.002), non-endometrioid histology (11.9% vs. 2.85%, p = 0.018), and high-intermediate/high-risk (HIR/HR) groups (59.52% vs. 37.80%, p = 0.001). POLEmut-p53abn (N = 4) and POLEmut-MMRd-p53abn (N = 10) tumors showed advanced stages (75% and 40% FIGO III-IV, respectively), in contrast to classical POLEmut tumors (6.7% FIGO III-IV), and higher rates of nodal metastases. Conclusions: Co-occurrence of molecular classifiers, including triple-classifier tumors, correlates with more adverse profiles and may undermine current stratification paradigms. This study emphasizes the need to further investigate and refine molecular risk models to account for overlapping profiles.