Determination of prognostic factors and optimal adjuvant therapy in patients with FIGO stage III endometrial cancer—a multi-institutional cohort study

Background: This study aimed to identify prognostic factors and assess which high-risk subgroups would benefit the most from the combination of chemotherapy and radiotherapy in patients with stage III endometrial cancer. Methods: A retrospective analysis was conducted with a cohort of 294 patients diagnosed with stage III endometrial cancer. All of whom underwent comprehensive surgical staging and adjuvant treatment between 2009 and 2021. Results: The median follow-up period was 42 months. Age over 60 years, substage IIIC2, and high grade or non-endometrioid histology were associated with poorer cancer-specific and overall survival (OS), though only age over 60 emerged as an independent adverse prognostic factor. Across the full cohort, survival did not differ significantly by adjuvant treatment modality. However, among patients aged over 60 years, adjuvant radiotherapy alone was associated with the lowest 5-year OS (42.3%), compared to chemotherapy alone (53.4%) and combined chemoradiotherapy (68.7%). In multivariate analysis, patients in this age group who received radiotherapy alone had significantly worse OS compared to those who received combined chemotherapy and radiotherapy (hazard ratio (HR) 3.15, 95% confidence interval (CI): 1.05–9.47, p = 0.04). Conclusions: The result of this real-world, multi-institutional cohort study showed that age over 60 years was a poor prognostic factor for stage III endometrial cancer patients. Combining adjuvant chemotherapy with radiotherapy was associated with the best survival outcomes, but this was only significant for patients aged over 60 years. Further prospective investigations of adjuvant therapies are warranted.