Is the sarcomatous component (homologous vs heterologous) the prognostic “driving force” in early-stage uterine carcinosarcomas? A retrospective multicenter study

Purpose: Uterine carcinosarcomas (UCSs) are aggressive biphasic malignancies, with a carcinomatous/epithelial component and a sarcomatous/mesenchymal counterpart. The aim of this study was to evaluate the impact of the sarcomatous component (homologous vs heterologous) on the overall survival (OS) and progression-free survival (PFS). Methods: This is a multicenter observational retrospective study conducted in patients with stage I and II UCSs. Results: Ninety-five women with histological diagnosis of early-stage UCSs were retrieved: 60 (63.2%) had tumors with homologous sarcomatous components, and 35 (36.8%) with heterologous. At univariate analysis, a stromal invasion ≥ 50%, the presence of clear cell, serous or undifferentiated carcinomatous component, the heterologous sarcomatous component and FIGO stage IB and II were shown to be variables with a statistically significant negative impact on PFS. Similarly, a depth of invasion ≥ 50%, the heterologous sarcomatous component and FIGO stage IB and II were statistically negative prognostic factors also concerning OS. At multivariate analysis, only the heterologous sarcomatous component was confirmed to be a statistically significant negative prognostic factor both on PFS (HR 2.362, 95% CI 1.207-4.623, p value = 0.012) and on OS (HR 1.950, 95% CI 1.032-3.684, p = 0.040). Conclusion: Carcinomatous and sarcomatous components both played a role in tumor progression and patients' survival. However, only the sarcomatous component retained a statistical significance at the multivariable model suggesting its preeminent prognostic role in early-stage UCSs.