Comparison of spread patterns and survival outcomes in uterine carcinosarcoma versus grade 3 endometrioid endometrial cancer

PURPOSE: To compare the clinicopathologic characteristics, dissemination patterns, and survival outcomes of uterine carcinosarcoma (CS) and grade 3 endometrioid adenocarcinoma (G3EAC), focusing on nodal distribution and the impact of complete surgical staging. METHODS: This retrospective cohort study included 105 patients (43 CS, 62 G3EAC) who underwent primary surgical treatment at a single tertiary center between 2000 and 2016. A focused analysis was performed on a high-quality subgroup of 80 patients (76.2%) who underwent systematic pelvic and para-aortic lymphadenectomy. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier methods, and independent prognostic factors were evaluated via Cox proportional hazards regression models. RESULTS: CS patients were significantly older than G3EAC patients (p = 0.005). While CS showed lower rates of deep myometrial invasion (44.2% vs. 67.7%; p = 0.016), it was associated with significantly higher positive peritoneal cytology (30.8% vs. 7.0%; p = 0.002). Overall lymph node metastasis rates were comparable between the groups (35.9% vs. 24.6%; p = 0.230). CS was associated with a significantly lower 5-year PFS (35.6% vs. 63.4%; p = 0.042), particularly in Stage IA disease (median PFS 7.7 months), and a trend toward lower 5-year OS (41.1% vs. 64.0%; p = 0.088). Multivariable analysis identified advanced age as the sole independent predictor of poor prognosis (OS HR 1.043, p = 0.021; PFS HR 1.039, p = 0.032). Notably, combined chemoradiotherapy (CRT) effectively eliminated the survival gap between histologies (5-year OS: 72.7% for CS vs. 70.0% for G3EAC; p = 0.590). CONCLUSION: Uterine carcinosarcoma exhibits minimal local invasion but high systemic aggressiveness. Traditional markers of local spread, such as myometrial invasion, are less predictive for CS. Systematic surgical staging remains essential, and multimodal adjuvant CRT is crucial to mitigating the inherent survival disadvantage of CS.