ABSTRACT
This chapter discusses the most up-to-date literature on retreatment of spinal metastases with stereotactic body radiotherapy (SBRT) and describe our experience with important spine SBRT techniques. The spine is the most common site for bony metastases and may be involved in up to 40% of all patients with cancer. However, shorter fractionation schemes for palliation of bone metastases have been the subject of multiple large randomized trials in the late 1990s and early 2000s, which included patients with spinal metastases. Once accurate models of prior radiation dose are obtained and reirradiation dose constraints for organs-at-risk determined, SBRT planning for retreatment is much the same as would occur if no prior radiation had been done. Sahgal et al. published a report comparing reirradiation spinal cord doses in 5 patients who developed radiation myelopathy compared to 14 control cases. Accurate contouring of the spinal cord is essential, as it is the primary dose-limiting structure.
