Prognostic factors and the impact of neoadjuvant chemotherapy on the development of metastasis in patients with undifferentiated pleomorphic sarcoma of soft tissue

Background: Although undifferentiated pleomorphic sarcoma (UPS), previously termed as malignant fibrous histiocytoma (MFH), is one of the most common soft tissue sarcomas, the number of studies focusing on UPS remains limited. This retrospective study aimed to identify prognostic factors and to assess the clinical impact of chemotherapy on the development of metastasis in patients with UPS. Methods: This study included 147 patients with UPS who underwent tumor resection. The associations of various parameters with oncological outcomes were investigated. Furthermore, the efficacy of chemotherapy against the development of metastatic disease has been investigated in patients with localized UPS. Results: The 5-year disease-specific and local recurrence-free survival rates were 71.7% and 61.6%, respectively. Metastatic disease at diagnosis (hazard ratio [HR], 16.7; P < 0.001) and trunk involvement (HR, 2.6; P = 0.015) were independently associated with disease-specificsurvival. R1/R2 resection (HR, 2.3; P = 0.008) and metastatic disease at diagnosis (HR, 5.2; P = 0.003) were independently associated with local recurrence-free survival. Among 39 patients who underwent neoadjuvant chemotherapy, 10 (25.6%) showed a good response (tumor necrosis ≥ 90%) to the neoadjuvant chemotherapy, and the responders showed a significantly higher metastasis-free survival rate than non-responders (P = 0.034). Conclusions: This study showed that metastatic disease at diagnosis, deep location, and incomplete resection are risk factors for poor oncological outcomes in patients with UPS, and that effective neoadjuvant chemotherapy decreases metastatic disease. The development of effective anticancer agents and methods for predicting of the chemotherapeutic effects is warranted to improve the clinical outcomes in patients with UPS.