Local Control and Toxicity Outcomes After Stereotactic Body Radiation Therapy for Metastatic Osteosarcoma in Pediatric Patients.

BACKGROUND

Pediatric osteosarcoma is an aggressive bone malignancy that presents significant challenges due to high rates of metastatic disease and relapse. It is often treated with palliative radiotherapy for symptom control, but achieving definitive local control (LC) with radiotherapy alone is challenging given its radioresistance. LC may be potentially improved by utilizing stereotactic body radiation therapy (SBRT) to deliver high biologically equivalent doses (BED).

METHODS

This study evaluated the LC outcomes of pediatric patients with osteosarcoma and unresectable metastatic disease who were treated with SBRT. Progression-free survival (PFS), overall survival (OS), and toxicities were assessed as secondary endpoints.

RESULTS

The study included seven patients who received 34 courses of SBRT. The median age at diagnosis was 13.1 and 17.1 years at first SBRT. The common sites for SBRT were extraspinal osseous metastases (56%), pulmonary/mediastinal (29%), and spine (9%). At a median follow-up of 6 months on a per-lesion analysis, LC was achieved in 88% of lesions, with four lesions failing locally. All four local failures were found in patients receiving a BED ≤48 Gy. The median distant PFS was 2.4 months. Toxicities were present in four patients, all of which resolved with supportive treatment.

CONCLUSIONS

Our study demonstrated that SBRT is safe and effective at achieving LC in pediatric patients with unresectable metastatic osteosarcoma, though distant progression can limit survival outcomes. Further studies evaluating SBRT in combination with other therapies are needed to address distant progression.