SABR Deemed Safe and Effective for Oligometastatic Soft Tissue Sarcoma

Stereotactic ablative radiotherapy (SABR) has demonstrated safety and efficacy in patients with oligometastatic soft tissue sarcoma (STS), according to researchers. They reported their findings in Radiotherapy and Oncology.

In this observational, multicenter study, researchers analyzed data from 138 patients with oligometastatic STS who were treated with SABR from 2010 to 2022. The most common primary STS site was the limbs (36.3%), followed by the trunk (27.5%) and pelvis (26.8%).

Most patients (71%) had lipo/leio/synovial/undifferentiated pleomorphic sarcoma, 59.4% had grade 3 disease, and 55.8% had de novo oligometastases. The same percentage of patients (55.8%) had a prior metastasectomy. Patients had received no prior systemic therapy (38.4%), 1 prior line (38.4%), or 2 or more prior lines (23.2%).

The median biologically effective dose of SABR was 98.9 Gy (range, 35.7-180 Gy). The median follow-up was 42.5 months.

The median overall survival (OS) was 39.7 months. In a multivariate analysis, shorter OS was associated with worse performance status (hazard ratio [HR], 1.68; 95% CI, 1.10-2.57; P =.016) and higher disease grade (HR, 1.76; 95% CI, 1.02-3.01; P =.039).

In-field recurrence was observed in 11.5% of patients, distant metastases occurred in 80.4% of patients, and polymetastatic progression occurred in 54.3% of patients.

The median local control was not reached, the median distant progression-free survival was 9.7 months, and the median time to polymetastatic progression was 27.8 months. The median time to new systemic therapy was 19.5 months.

Acute toxicity occurred in 13 patients. The most common acute toxicities were asthenia, esophagitis, and pain.

Late toxicities included cough (n=3), dyspnea (n=2), pneumonitis (n=1), and esophagitis (n=1). There were no grade 3 or higher acute or late toxicities.

“With this large multicenter analysis, we report favorable outcomes for OM [oligometastatic] STS treated with SABR,” the researchers concluded. “Treatment tolerance was excellent and OS satisfactory. One of five patients is free of progression at 2 years.”

This article originally appeared on Cancer Therapy Advisor