Non-endometrioid endometrial cancer: analysis of recurrence pattern and identification of prognostic and treatment factors affecting recurrence and survival.

PURPOSE: We investigated the characteristics of recurrence pattern and survival of patients with non-endometrioid endometrial cancer (NEEC) and attempted to identify prognostic and treatment factors affecting disease-free survival (DFS) and overall survival (OS) of these patients. METHODS: Fifty-seven patients with histologically confirmed International Federation of Gynecology and Obstetrics (FIGO) stage IA-IVA NEEC from February 2003 to December 2021 were retrospectively analyzed. RESULTS: The 5­year DFS and OS rates of the total cohort were 50.6% and 56.1%, respectively. Recurrence occurred in 28 patients (49.1%) during follow-up, and the most common recurrence pattern was distant metastasis (DM; 78.6% of total recurrences). The occurrence of relapse significantly reduced 5­year OS (recurrence group vs. non-recurrence group: 12.5% vs. 100%; p < 0.001). In univariate analysis, adjuvant radiotherapy (RT) group showed significantly higher 5­year DFS (56.7% vs. 37.9%; p = 0.04), local recurrence-free survival (91.6% vs. 50.5%; p = 0.01), and regional recurrence-free survival (88.2% vs. 56.5%; p < 0.01) than the non-RT group. In multivariate analysis, advanced FIGO stage was identified as a negative prognostic factor for DFS and OS. Lymphovascular space invasion (LVSI) and adjuvant RT were independent prognostic factors for DFS. CONCLUSION: The most common recurrence pattern observed in patients with NEEC was DM. FIGO stage and LVSI were identified as prognostic factors for survival, and RT was identified as a therapeutic modality that could increase DFS. To improve the OS of patients with NEEC, the addition of effective chemotherapy that can reduce DM may be important.