The relationship between histopathological data and molecular alterations with oncological outcomes in...

To identify molecular subgroups in endometrioid endometrial cancer (EEC), evaluate their association with clinicohistopathological characteristics, and define low-intermediate risk groups by integrating these parameters.

This retrospective-cohort study included 1,040 patients who underwent surgery between January 2000 and June 2022. Among 900 EEC cases, 72 recurred. Patients with tumor recurrence (n=62) and those without (n=52) were matched. POLE exons 9-14 were examined using Sanger sequencing. p53 and mismatch repair (MMR) protein expression were assessed via immunohistochemistry.

The molecular subgroups were POLE mutation (POLE-mut) 5%, mismatch repair-deficient (MMR-d) 43%, p53 mutation (p53-mut) 5%, and non-specific molecular profile (NSMP) 42%. 5% of cases displayed multiple molecular mutations. POLE-mut were more prevalent in high-grade tumors (p=0.026). MMR-d tumors exhibited higher rates of lymphovascular space invasion and myometrial invasion ≥50% (p=0.032, p=0.020). No recurrences occurred in POLE-mut tumors (p=0.002), while MMR-d was significantly associated with recurrence (p=0.002). Median disease-free survival (DFS) for MMR-d, p53-mut, and NSMP were 34, 49, and 107 months, respectively. Median overall survival (OS) for these groups was 128, 102, and 181 months. Multivariate Cox-regression analysis employing the Backward-Stepwise method identified stage as the strongest predictor of DFS, and grade and stage as predictors of OS.

POLE mutations were linked to the most favorable molecular prognostic factor. NSMP cases showed the longest DFS and OS, while p53-mut had the shortest OS. Except for POLE, molecular features alone were insufficient for establishing risk groups, highlighting the continued importance of histopathology in EEC management.