SABR for Sarcoma Lung Metastases: Indications for Treatment and Guidance for Patient Selection

Abstract

IntroductionThe lungs are the most common site of metastasis for patients with soft tissue sarcoma. Stereotactic ablative radiation therapy (SABR) is commonly employed to treat lung metastases among select sarcoma patients with limited disease burden. We sought to evaluate outcomes and patterns of failure among sarcoma patients treated with SABR for their lung metastases. MethodsWe performed a retrospective review of patients treated at a tertiary cancer center between 2006-2020. Patients’ disease status at the time of SABR was categorized as either oligorecurrent or oligoprogressive. The Kaplan-Meier method was used to estimate disease outcomes. Uni- and multivariable analyses were conducted using Cox proportional hazards model. ResultsWe identified 70 STS patients treated with SABR to 98 metastatic lung lesions. Local recurrence-free survival following SABR treatment was 83% at 2 years. On univariable analysis, receipt of comprehensive SABR to all sites of pulmonary metastatic disease at the time of treatment was associated with improved PFS (HR 0.51 [0.29-0.88], p=0.02). On multivariable analysis, only having systemic disease controlled at the time of SABR predicted improved PFS (Median PFS 14 months vs 4 months; HR 0.37 [0.20-0.69], p=0.002) and OS (Median OS 51 months vs 14 months; HR 0.17 [0.08-0.35], p<0.0001). ConclusionSABR provides durable long-term LC for sarcoma lung metastases. The most important predictor for improved outcomes was systemic disease control. Careful consideration of these factors should help guide decisions in a multidisciplinary setting to appropriately select the optimal candidates for SABR.