Trial for Salvage Re-Irradiation of Metastatic Spine Lesions Using Single-Fraction Stereotactic Radiosurgery

Inclusion Criteria: * Patients must have histologic or cytologic proof of a non-hematologic malignancy confirmed by MSKCC pathologic review * Patients must have radiographic evidence of malignancy in the spine or cauda equina region (L2 to sacrum) which is suitable for radiation therapy * Patients must have received prior external beam radiation therapy to the region proposed for SRS re-irradiation at least 6 months prior to planned re-irradiation * For patients who were previously treated at an outside institution, adequate records must be available to determine the true dose the cord/cauda received during prior RT. Sufficiency of the treatment records will be assessed and signed-off by the Medical Physics investigator. * Patients must have demonstrated progression of disease on MRI or CT assessment of the spinal cord/cauda within the previous radiation field o progression may consist of an increase in maximal dimension of the tumor by ≥20%, compromise of the spinal cord/cauda equina and/or exiting spinal nerves (assessed clinically or radiographically), or both. * Target lesion size for re-irradiation must be ≤ 2 vertebral bodies * KPS ≥ 60% * Age ≥ 18 years old Exclusion Criteria: * Patients with a life expectancy of \< 6 months as predicted by the Adult Comorbidity Index (ACE-27, see Appendix 1). * Patients with intradural or intramedullary lesions, or lesions with \< 2mm distance from tumor to spinal cord * Patients with circumferential epidural disease * Systemic …