BackgroundIt is known that preoperative Prognostic Nutritional Index (PNI) is useful in predicting prognosis in gastrointestinal diseases and that preoperative improvement of nutritional status improves prognosis. However, there have been few large-scale reports examining the prognostic value of PNI in soft tissue sarcomas. Therefore, the aim of this study is to investigate whether the PNI can be useful for predicting overall survival in soft tissue sarcoma. MethodsBetween January 2006 and March 2022 at our hospital, 111 patients with pathologically diagnosed soft tissue sarcoma were included, retrospectively. Several nutritional or inflammatory biomarkers such as PNI were calculated from the pretreatment blood sample results. The patients were classified into two groups (low and high groups) based on the median value of each parameter. Overall survival was analyzed by the Kaplan‒Meier method and log-rank test. Univariate and multivariate analyses using the Cox proportional hazards model were used to investigate prognostic factors for overall survival. ResultsThe median overall survival was 24.3 months (mean 37.3 months), and the high PNI group had a significantly longer overall survival than the low PNI group (p < 0.0001). PNI was the most significant univariate factor for overall survival among other nutritional and inflammatory parameters (HR: 5.64, 95% CI: 2.26–14.12, p = 0.0002). The multivariate proportional hazards model was built using variables with prognostic potential as suggested by previous analysis with respect to patient characteristics and PNI. As potential confounding factors, we included PNI, stage, age, and tumor location. PNI was also an independent prognostic factor in multivariate analysis (HR: 7.02, CI: 2.52–19.40, p = 0.0002). ConclusionPNI is a useful prognostic factor among various parameters for overall survival in patients with soft tissue sarcoma.