Targeted Oligometastatic Radiation in Pediatric and Young Adult Patients With Soft Tissue and Bone Sarcoma

Children, adolescents and young adults (AYA) with metastatic sarcoma have poor event free survival (EFS) and overall survival (OS). Recent retrospective studies suggest there is both an EFS and OS benefit to consolidating all sites of disease with radiation therapy (RT), referred to as consolidative radiation therapy (cRT). However, results from such retrospective studies might be confounded by selection bias as patients with a small burden of metastatic disease are most likely to undergo cRT. Thus far, ongoing prospective studies evaluating the benefit of cRT in the oligometastatic sarcoma setting have been limited to the adults and include sarcoma histologies that are not relevant to children and AYA. Therefore, to address this question in children and AYA, the investigators are proposing a single arm phase II study to estimate the preliminary efficacy of cRT in oligometastatic pediatric bone or soft tissue sarcoma. Given the investigators historical patient population, the investigators expect that approximately 70% of patients enrolled on the study will be diagnosed with either Ewing sarcoma (EWS) or rhabdomyosarcoma (RMS). The investigators primary hypothesis is that the hazard ratio (HR) for EFS of those receiving cRT compared to those did not receive cRT, constructed using historical control data, is less than or equal to 0.5. To address this hypothesis, 32 evaluable patients will need to be enrolled. The investigators will also determine the feasibility of longitudinal quantification of circulating tumor DNA (ctDNA). This may serve as a biomarker of response to therapy and provide additional prognostic value to existing anatomic and metabolic imaging. This trial seeks to enhance outcomes for metastatic sarcoma in the pediatric and AYA setting and may potentially redefine treatment paradigms for this challenging disease.