LINAC-based spinal stereotactic radiosurgery

The authors' report on the use of a prototype spinal stereotactic radiosurgery frame which was employed for the treatment of 9 patients who presented with recurrent neoplastic involvement of the spinal column. All patients had failed standard therapy consisting of surgery, external fractionated radiation therapy, and/or chemotherapy. Eight of the lesions represented metastatic tumors in the vertebral column, one of the lesions was a primary osteosarcoma involving multiple vertebral bodies. The lesions were found at multiple levels, from the cervical through the sacral region. Six out of the 9 patients presented with epidural compression: 4 of the 9 patients with evidence of myelopathy: 2 of the 9 patients with radicular symptoms secondary to compression from the tumor, and 1 patient was free of any compressive symptoms. All patients had pain requiring narcotics. Patients were treated with a median radiosurgical dose of 800 cGy (range 800-1.000) with a median of 1 isocenter (range 1-7 isocenters) and median normalization of 80% to the isodose contour (range 80-160). Median dose delivered to the already prior irradiated spinal cord was 179 cGy (range 52-320 cGy) with a median spinal cord dose of 34 (range 4-68). To date, there have been three minor complications: one radiation-induced esophagitis which was treated medically: one wound infection, and 1 patient requiring an additional 24 h of hospitalization stay. There have been no major complications. To date, 5 of the 9 patients have died, all from causes unrelated to the spinal radiosurgery. Three out of the 9 patients have been followed for more than 1 year. In all 3, there was radiographic regression of the tumor and epidural compression. In 2 patients, there was histologic confirmation of absence of tumor in the treated site: in 1 patient. no tumor was found at postmortem. 12 months after treatment, when the patient died of unrelated causes. Although the number of patients followed is limited, the phase I study clearly shows the technical feasibility of spinal radiosurgery for the control of metastatic involvement of the vertebral column even in the face of epidural compression.