Proton SBRT for Spinal Metastasis

Inclusion Criteria: 1. Histologic proof or unequivocal cytologic proof of nonhematologic malignancy. This may be obtained from either the primary or any metastatic site. 2. Participants must have radiographic evidence of spinal metastasis on MRI. 3. Participants must have a complex case that is unable to be effectively treated with photon SBRT, defined as inability to develop a photon SBRT plan that achieves adequate coverage (≥80% PTV coverage) with a prescription dose of 30 Gy in 5 fractions. Such cases include: 1. Extensive paraspinal disease 2. Reirradiation setting 3. Epidural extension (Bilsky grade ≥1c) 4. Age ≥ 18 years. 5. Eastern Cooperative Oncology Group (ECOG) performance status ≤2 (Karnofsky \>60%). 6. Patients of childbearing potential (male or female) must practice adequate contraception due to possible harmful effects of radiation therapy on an unborn child. 7. Patients must have the ability to understand and the willingness to sign a written informed consent document. 8. All patients must be informed of the investigational nature of this study and must be given written informed consent in accordance with institutional and federal guidelines. Exclusion Criteria: 1. Participants may not have a spinal metastases case amenable to standard of care photon SBRT planning techniques that achieve ≥80% PTV coverage with a prescription dose of 30 Gy in 5 fractions. 2. Patients who are unable to receive MRIs will be excluded from the study since MRIs will be critical in treatment planning. 3. Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.