Single- vs. Two-Fraction Spine Stereotactic Radiosurgery for the Treatment of Vertebral Metastases

Eligibility Criteria

• * Karnofsky Performance Status (KPS) ≥ 70
• * RPA class 1 (KPS \>70 AND controlled systemic disease) or RPA Class 2 (KPS \>70, uncontrolled systemic disease OR KPS ≤70, age ≥54, no visceral metastases)44 (see Appendix II)
• * Vertebral metastases from C3 to L5 based on bone scan, CT, PET, or MRI.
• * Vertebral metastases must be (1) solitary, (2) at two contiguous levels, or (3) a maximum of three separate sites, with a maximum of two contiguous levels.
• * Radioresistant metastases are permitted (including sarcomas, melanomas, and renal cell carcinomas).
• * Patients with epidural disease are permitted so long as there is no cord compression.
• * Paraspinal extension is permitted, so long as the paraspinal component is ≤5 cm
• * Multiple small metastatic lesions (\<20% vertebral body involvement) of no clinical correlate are permitted, and not included in the irradiated segments as per RTOG 0631
• * History and physical within four weeks of registration.
• * Negative pregnancy test within four weeks of registration for women of childbearing potential.
• * Diagnostic spine MRI with and without contrast within four weeks of registration
• * Neurological exam within four weeks of registration to rule out rapid neurological decline. Mild to moderate neurological deficits are acceptable, as long as distance between lesion and spinal cord is ≥3 mm
• * Patients may have prior EBRT at the index site.
• * Informed consent of the participant.
• * Lesions at C1-2 or S1-Coccyx.
• * Hematologic malignancies including lymphoma and myeloma.
• * Multiple primary cancers.
• * Primary neoplasms of the spine
• * Prior corpectomy, kyphoplasty/vertebroplasty, or instrumentation at the site of planned sSRS.
• * Spinal cord compression.
• * Paraspinal mass \>5 cm.
• * Patients with rapid neurologic decline.
• * Bony retropulsion resulting in neurologic deficit.
• * Patients with contraindications to MRI.
• * Patients allergic to intravenous contrast for MRI or CT.
• * Patients with emergent spinal cord compression.
• * Patients with mechanical instability of the spine.
• * Patients with active connective tissue disease.
• * Patients who previously underwent sSRS to the vertebrae of interest.
• * Patients with diffuse or multilevel metastatic spinal disease with \>20% involvement of vertebral bodies, defined as involvement of \>5 vertebral levels.
• * Inability to participate in study activities due to physical or mental limitations.
• * Inability or unwillingness to return for all required follow-up visits and imaging.
• * Inability to deliver sSRS, either 18 Gy in one fraction, or 24 Gy in two fractions.