Prophylactic Radiotherapy of MInimally Symptomatic Spinal Disease

Inclusion Criteria: 1. Histologically-confirmed solid tumor malignancy with greater than 5 sites of metastatic disease detected on cross-sectional imaging. 2. Has high-risk bone metastases that are asymptomatic or minimally symptomatic (not requiring opioids). High risk metastases are defined as: 1. Bulkiest sites of spinal osseous disease ≥ 2cm, 2. Disease at junctional levels, including the thoracic apex (Occiput to C2, C7-T1, T12-L2, and L5- S1) 3. Disease with posterior element involvement, including interspinous, unilateral, or bilateral facet joints. 4. Vertebral body compression deformity \> 50%. 3. Eastern Cooperative Oncology Group (ECOG) performance status 0 - 2. 4. Age ≥ 18 years. 5. Able to provide informed consent. 6. Patients at reproductive potential must agree to practice an effective contraceptive method. Women of childbearing potential must not be pregnant or lactating. Exclusion Criteria: 1. Previous RT to the intended treatment site that precludes developing a treatment plan that respects normal tissue tolerances. 2. Serious medical co-morbidities precluding RT. 3. Pregnant or lactating women. 4. Target lesion(s) is/are complicated bone metastases that include clinical or radiological evidence of spinal cord compression or impending pathological fracture. 5. Leptomeningeal disease. 6. Patients whose entry to the trial will cause unacceptable clinical delays in their planned management.