Comparison of Features and Outcomes of Undifferentiated Pleomorphic Sarcoma of Bone and Soft Tissue

Background: This investigation compared outcomes of patients with undifferentiated pleomorphic sarcoma of soft tissue (UPS-S) to UPS of bone (UPS-B).

Methods: The Surveillance, Epidemiology, and End Results database was reviewed from 1975-2016. Disease-specific survival (DSS) was estimated using Kaplan-Meier, and a multivariable Cox regression model identified factors prognostic of DSS. The UPS-S cohort consisted of 4529 patients and the UPS-B cohort consisted of 200 patients. The smaller UPS-B cohort was bootstrapped to create a size-matched cohort of 4500 patients.

Results: The median age of patients with UPS-S was 67 (54;78) y compared to 55 (40;69) y for UPS-B patients (P < 0.001). For UPS-S, the median DSS was 317 mo compared to 70 for UPS-B (P = 0.020). On multivariable analysis for UPS-S, age (HR, 1.018; 95% CI, 1.01-1.03; P < 0.001), non-extremity tumors (HR, 1.490; 95% CI 1.14-1.95; P = 0.004), and AJCC Stage III (HR, 2.238; 95% CI 1.2-4.17; P = 0.011), and Stage IV (HR, 9.388; 95% CI 4.69-18.79; P < 0.001) disease were negative prognostic factors, while surgery (HR 0.234; 95% CI, 0.16-0.34; P < 0.001) was a positive prognostic factor. For UPS-B, tumor size > 8 cm (HR, 3.101; 95% CI, 1.09-8.75; P = 0.033) was the only prognostic factor identified.

Conclusions: The current study found a strong association between surgery and survival for UPS-B patients on a univariable analysis, but no treatment type was associated with survival in a multivariable model. Further research is needed to reliably inform the optimal treatment of these patients.