High rates of local control and improved survival were achieved with stereotactic body radiotherapy (SBRT) of metastatic lesions associated with inoperable sarcoma among children and young adults, according to results of a study published in Cancer.
The standard of care for pediatric patients with metastatic sarcoma is metastasectomy; however, for patients with inoperable disease, SBRT is an option. The aim of this study was to evaluate the use of SBRT in this population.
The multicenter, phase 2 trial treated 14 patients with unresected, osseous, metastatic nonrhabdomyosarcoma of soft tissue and bone with 5 fractions of SBRT of 40 Gy. The primary endpoint was lesion-specific local control at 6 months. Secondary endpoints included progression-free survival (PFS), overall survival (OS), toxicity, and pain response.
At baseline, the median patient age was 17 years, with 64% of patients younger than 18 years. There were 37 distinct sites of disease that were treated, with 57% of patients having all of their known metastatic sites treated.
During a median follow-up period of 6.8 months, 89% of patients achieved local control and 95% of patients achieved lesion-specific control at 6 months.
The median PFS was 6 months. PFS was 50% and 29% at 6 months and 12 months, respectively. The median OS was 24 months. All patients were alive at 6 months, and the 12- and 24-month OS was 84% and 50%, respectively.
There was no change in pain scores after SBRT.
A post hoc analysis demonstrated that total consolidation was associated with improved survival, with a median PFS of 9.3 months compared with 3.7 months among patients who received partial consolidation (P =.03). Similarly, the median OS was not yet reached among patients who underwent total consolidation compared with 12.7 months among patients who received partial consolidation (P =.02).
The majority of adverse events (AEs) reported were grade 1 (75%), with 2 patients experiencing a grade 3 AE, including 1 case of esophagitis and 1 case of bone necrosis.
The authors concluded that “SBRT can be used for the treatment of unresectable bone metastases in children and young adults with metastatic NRMS sarcomas of bone and soft tissue.” They added that because the treatment options for this population are limited, “SBRT to metastatic sites should be considered when feasible.”
Elledge CR, Krasin MJ, Ladra MM, et al. A multi-institutional phase 2 trial of stereotactic body radiotherapy in the treatment of bone metastases in pediatric and young adult patients with sarcoma. Cancer. Published online November 10, 2020. doi:10.1002/cncr.33306