Introduction/Background*Uterine carcinosarcomas (UCSs) are aggressive biphasic malignancies, with a high grade carcinomatous/epithelial component and a high grade sarcomatous/mesenchymal counterpart. Several studies identified the carcinomatous part as the main factor affecting the aggressive behaviour of UCSs. However, other studies reported that the sarcomatous component, especially the presence of heterologous elements, was associated with a worse prognosis. The prognostic ‘driving force’ is not completely clear for these kind of tumours. For this reason, the aim of our study was to evaluate the impact of the sarcomatous component (Homologous vs Heterologous) on the overall survival (OS) and progression-free survival (PFS).

Methodology This is a multicenter observational retrospective study conducted in patients with stage I and II UCSs.

Result(s)*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. Tumors with a sarcomatous heterologous component were significantly larger than the homologous (T ≥ 50 mm: 82.9% vs 51.7%, p-value=0.002) and presented more often lymph-vascular space invasion (62.9% vs 25.9% respectively in patients with heterologous and homologous component, p-value=0.001). At univariate analysis, a stromal invasion ≥ 50%, the presence of clear cell, serous or undifferentiated carcinomatous component, the heterologous sarcomatous component and the 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 the 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*In conclusion, in our large series of UCSs, both carcinomatous and sarcomatous components 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.