MRIdian "RADAR" Trial

Inclusion Criteria: Male and female participants ages ≥ 18. Solid tumors causing MESCC for which surgery is an option as first-line treatment. Tumor histologies eligible for treatment include breast, prostate, sarcoma, melanoma, gastrointestinal types, NSCLC and renal cancers. Other solid malignancy types are also allowed at discretion of investigator if not specifically excluded by criteria. MRI of involved spine within 4 weeks prior to registration to determine extent of spine involvement. Bilsky scale ≥ 1c MESCC with tumor ≤ 1 mm from the spinal cord or cauda equina nerve roots anywhere from C1 to terminus of cauda equina on screening MRI. Protocol defined MESCC must involve no more than 3 contiguous vertebral levels. MESCC can involve multiple non-contiguous spinal canal regions within those 3 contiguous vertebral levels. Karnofsky performance score ≥60 Survival prognosis ≥3 months Medical status allowing surgery. Neurologic exam within 1 week prior to registration and again within 1 week of first treatment to rule out severe neurologic deficits caused by disease at site of cord compression. Patients with mild to moderate cord neurologic signs are eligible if they are improved or stabilized by steroid. These neurologic signs include radiculopathy, dermatomal sensory change, and muscle strength of involved extremity 4/5 (lower extremity for ambulation or upper extremity for raising arms and/or arm function). All patients must be ambulatory. Numerical Rating Pain Scale within 1 week prior to registration (back pain permitted for enrollment) Spine instability neoplastic score < 14 a. An exception to this criterion may be made if the patient is evaluated by a spinal surgeon and the surgeon defers surgery. Willing and able to undergo daily MRI during treatment Willingness and able to use an acceptable method of contraception during the study and for at least 6 months after stopping the therapy. Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2 History and physical within 2 weeks prior to registration Patients must provide study specific informed consent prior to study entry. Exclusion Criteria: Unknown primary histology Patients with rapid neurologic decline. Bony retropulsion causing neurologic abnormality Non-ambulatory patients. Prior radiation to the involved site. Inability to have an MRI Pre-existing or concomitant neurological problems not related directly to MESCC (e. g., neurologic deficits due to brain metastases) Very radiosensitive tumor histology (e.g., myeloma, seminoma, germ cell tumors, leukemia, and lymphoma) Patients with impaired decision-making capacity.