Stereotactic Body Radiotherapy for Sarcoma Pulmonary Metastases.

Stereotactic body radiotherapy (SBRT) is standard for patients with inoperable early-stage NSCLC and is frequently utilized for pulmonary metastases with limited data. We hypothesized that SBRT for sarcoma pulmonary metastases would achieve high rates of local control with acceptable toxicity and that patients with oligometastatic disease may achieve prolonged survival following SBRT. This IRB-approved retrospective review included patients at our institution treated with SBRT for sarcoma pulmonary metastases. SBRT was delivered in 1 - 8 fractions at the discretion of the treating clinician. Patients were classified as oligometastatic if they had ≤ 3 sites of disease or progression at ≤ 3 sites of metastatic disease. Cumulative incidence of local failure (LF) was calculated using competing risks analysis and compared across groups using Grey's test. LF was defined as progression in the SBRT field on 2 consecutive follow-up scans with LF date backdated to the earliest scan showing progression. We also evaluated toxicity and overall survival from the time of SBRT. Overall survival (OS) was estimated using the Kaplan-Meier method and compared across groups using the Log rank test and Cox proportional hazards regression. Between 2011 and 2021, 69 patients with 101 sarcoma pulmonary metastases were treated with SBRT to a median dose of 48 Gy (range: 25 – 60 Gy) in 4 fractions (range: 1 – 8 fractions). The most common histologies were leiomyosarcoma (n = 20 patients), liposarcoma (n = 8 patients), and osteosarcoma (n = 7 patients). The median follow-up time from SBRT was 26.1 months (95% CI 20.9-34.4) and 19.8 months for patients alive at last follow-up. A total of 35 patients (51%) were oligometastatic. The cumulative incidence of LF at 12 and 24 months was 6% (95% CI 3% to 12%) and 11% (95% CI 6% to 19%), respectively. The cumulative incidence of LF was significantly lower for peripheral compared to central lesions (12-month LF 11.4% vs 0% and 24-month LF 20.7% vs 0%, p = 0.002). OS at 12 and 24 months was 76% (95% CI 66% to 87%) and 52% (95% CI 40% to 67%), respectively. On univariable analysis, OS was significantly higher for patients with oligometastatic disease (12-month OS 85% vs 66%, p < 0.001, HR [95% CI] 0.29 [0.14, 0.59]) and Karnofsky Performance Status ≥ 90 (12-month OS 83 vs 63%, p =.03, HR [95% CI] 0.48 [0.24, 0.93]) but not age, sex, or time between initial pathologic diagnosis and SBRT. Among patients with oligometastatic disease, the median time to next systemic therapy or last follow-up was 10.0 months (range: 1 to 44.4 months). Three patients (4.3%) had grade 2 pneumonitis, and one patient (1.4%) had grade 2 esophagitis. No patients had ≥ grade 3+ toxicity. To the best of our knowledge, this is the largest series of patients treated with SBRT for pulmonary sarcoma metastases. SBRT offers a safe alternative to surgical resection with excellent local control. Minimal toxicity was observed. Patients with oligometastatic disease had prolonged survival after SBRT. [ABSTRACT FROM AUTHOR]