Stereotactic Body Radiotherapy (SBRT) for Pulmonary Metastases in Ewing Sarcoma, Rhabdomyosarcoma, and Wilms Tumors

Inclusion Criteria: * Diagnosis of Ewing sarcoma, rhabdomyosarcoma, osteosarcoma, non-rhabdomyosarcoma soft tissue sarcoma, Wilms tumor or other primary renal tumor (including clear cell and rhabdoid) * Age ≤ 21 years; * Must be capable of treatment without general anesthesia * Lesion size 8 mm - 3 cm * Subjects who have lesions within 2 cm of central structures, will be eligible on a case by-case basis * Pulmonary metastases found at relapse (does not have to be first relapse); no more than 3 lesions per hemi-thorax will be treated but other lesions in the lung may be present * Greater than 5 weeks from doxorubicin at the time of consent, with radiation to be initiated no less than 6 weeks from doxorubicin * Informed consent/assent * Life expectancy \>3 months * Pulmonary Function FEV1 ≥ 50% of predicted; * Concurrent immunotherapy is allowed Exclusion Criteria: * Prior whole-lung or hemi-thorax irradiation of greater than 12 Gy received less than 6 months prior to consent (focal radiotherapy to the thorax is not an exclusion) * Lesion larger than 3 cm in diameter * Patients for whom surgery would be deemed appropriate rather than radiotherapy