Intraoperative Radiotherapy Combined with Posterior Surgery for Spinal Metastases

Abstract

Patients with cancer often suffered from spinal metastasis, and spinal cord compression from spinal metastasis represents a substantial clinical problem. External beam radiotherapy (EBRT) or conventional surgical decompression of the spinal cord often results in unsatisfactory neurological recovery and local recurrence. To improve neurological recovery and local control in such cases, we introduced intraoperative radiotherapy (IORT) combined with posterior surgery in 1992. We report the results for neurological recovery and local control in patients who received IORT combined with posterior surgery. Between November 1992 and March 2009, 158 cases (133 patients) were treated using IORT combined with posterior surgery for spinal paresis due to spinal metastases of breast, renal, thyroid, colorectal, and lung cancer. 99 cases were nonambulatory and 59 cases ambulatory before surgery. After posterior decompression, a single large dose of electron beam irradiation was delivered to the exposed metastatic lesion. Percentage dose in the spinal cord was approximately 10 - 25% with a lead shield, however, scattering of electron beams spread from behind the shielded central spinal cord region to reach the posterior region of the vertebra body located directly anterior to the spinal cord. Median dose of IORT was 20 Gy (range, 10 - 35 Gy), and median energy was 16 MeV (range, 11 - 22 MeV). 61 cases were treated with EBRT before the surgery; the delivered median dose was 40 Gy (range, 7.5 - 60 Gy). 41 cases were treated with EBRT after the surgery; the delivered median dose was 35 Gy (range, 8 - 50.5 Gy). Neurologic improvement of at least one level according to Frankel's classification was attained in 106 cases (67%) with a median follow-up period of 12.8 months. Spinal paralysis completely disappeared after surgery in 34 cases (22%). Of all 158 cases, 136 cases (86%) were ambulatory after surgery. Of the 99 cases nonambulatory before surgery, 78 cases (80%) became ambulatory after surgery. Postoperatively, 14 cases (9%) experienced local recurrence and neurologic exacerbation of at least one level according to Frankel's classification. The median time to local recurrence was 10.6 months (range, 3.0 - 40.6 months) after the surgery. For all 158 cases, median survival time was 18.5 months (range, 0.5 - 111.8 months) after the surgery. One patient experienced radiation myelopathy, and another patient experienced radiation neuropathy of cauda equina during the follow-up period. IORT combined with posterior surgery is a useful technique for the treatment of spinal cord compression caused by spinal metastasis, offering significant neurologic recovery and a low rate of local recurrence.