Radiation Therapy in Resectable Intrathoracic Sarcomas. A Rare Cancer Network Study

Intrathoracic sarcomas (ITS) are considered rare tumors and have a dismal prognosis. We investigated outcomes and risk factors for local control (LC), disease-free survival (DFS), and overall survival (OS) in patients with resected nonmetastatic ITS treated with or without adjuvant radiation therapy (RT) and/or chemotherapy.

Patients from the Rare Cancer Network database were studied. A Kaplan-Meier estimate was used to assess survival curves, and Cox proportional hazards regression was used to assess risk factors for LC, DFS, and OS.

Between 2000 and 2017, 121 patients met inclusion criteria. The primary site was lung in 30%, mediastinum in 34%, and pleura in 36%. Thirty-nine percent and 32% received RT and chemotherapy. Median follow-up was 34 months (range, 2-141). LC, DFS, and OS at 10 years were 52%, 18.7%, and 7.2%, respectively. In multivariate analysis, RT (P = .003) and R1 margin status (P = .041) retained a significant association with LC. Only R1 resection (P = .002) remained associated with an increased risk of death in multivariate analysis. Overall, 7 patients (6%) developed grade 3 treatment-related chronic toxicity events.

This joint analysis revealed that OS remains modest in this group of patients, mainly given by the high risk of local and distant failure. Our results suggest that resected ITS can benefit from adjuvant RT.