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

Purpose: The lungs are the most common site of metastasis for patients with soft tissue sarcoma. SABR is commonly employed to treat lung metastases among select patients with sarcoma with limited disease burden. We sought to evaluate outcomes and patterns of failure among patients with sarcoma treated with SABR for their lung metastases. Methods and Materials: We performed a retrospective review of patients treated at a tertiary cancer center between 2006 and 2020. Patient 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 the Cox proportional hazards model. Results: We identified 70 patients with soft tissue sarcoma treated with SABR to 98 metastatic lung lesions. Local recurrence-free survival after 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 progression-free survival (PFS; hazard ratio [HR], 0.51 [0.29-0.88]; P = .02). On multivariable analysis, only having systemic disease controlled at the time of SABR predicted improved PFS (median PFS, 14 vs 4 months; HR, 0.37 [0.20-0.69]; P = .002) and overall survival (median overall survival, 51 vs 14 months; HR, 0.17 [0.08-0.35]; P < .0001). Conclusions: SABR provides durable long-term local control 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.