Systemic inflammation index is a predictive and prognostic factor in patients with liposarcoma or leiomyosarcoma treated with trabectedin.

Trabectedin is a chemotherapeutic agent that has shown activity in the treatment of patients with soft tissue sarcomas after failure of anthracycline-based therapy and the best results were recorded in the treatment of L-sarcomas. There is a need for prognostic and predictive factors that will help clinicians with therapy selection. In this study we aim to analyze treatment results, prognostic and predictive factors in patients treated with trabectedin in routine clinical practice. We retrospectively analyzed the medical records of patients who started treatment with trabectedin between 04/2008 and 09/2021. Demographic and clinical data were extracted, and markers of systemic inflammation, including neutrophil-to-lymphocyte ratio (NLR) and systemic inflammation index (SII), were calculated. We identified 251 patients, including 174 with complete baseline laboratory data. Objective responses were noted in 10.8% of patients, and disease stabilization was noted in 49.0%. Median PFS and OS were 5.26 months and 17.98 months, respectively. In the overall population, liposarcoma and metastasis-free interval (MFI) > 10 months were predictive factors for PFS, while female sex and MFI > 10 prognostic factors for OS. Among patients with available laboratory data, the median NLR at baseline was 2.87, and SII was 1047.26. In multivariate analysis, SII ≤ 670 significantly correlated with longer PFS but not with OS. Long-term results of trabectedin treatment in Polish patients with L-sarcomas are comparable to the results of other real-world evidence studies. In conclusion, the systemic inflammation index correlates significantly with PFS, is a simple marker available for daily clinical practice to identify patients most likely to benefit from treatment.