Stereotactic Ablative Radiotherapy for the Management of Spinal Metastases A Review

Importance Rising cancer incidence combined with improvements in systemic and local therapies extending life expectancy are translating into more patients with spinal metastases. This makes the multidisciplinary management of spinal metastases and development of new therapies increasingly important. Spinal metastases may cause significant pain and reduced quality of life and lead to permanent neurological disability if compression of the spinal cord and/or nerve root occurs. Until recently, treatments for spinal metastases were not optimal and provided temporary local control and pain relief. Spinal stereotactic ablative radiotherapy (SABR) is an effective approach associated with an improved therapeutic ratio, with evolving clinical application. Objective To review the literature of spinal SABR for spinal metastases, discuss a multidisciplinary approach to appropriate patient selection and technical considerations, and summarize current efforts to combine spinal SABR with systemic therapies. Evidence Review The MEDLINE database was searched to identify articles reporting on spinal SABR to September 30, 2018. Articles including clinical trials, prospective and retrospective studies, systematic reviews, and consensus recommendations were selected for relevance to multidisciplinary management of spinal metastases. Results Fifty-nine unique publications with 5655 patients who underwent SABR for spinal metastases were included. Four comprehensive frameworks for patient selection were discussed. Spinal SABR was associated with 1-year local control rates of approximately 80% to 90% in the de novo setting, greater than 80% in the postoperative setting, and greater than 65% in the reirradiation setting. The most commonly discussed adverse effect was development of a vertebral compression fracture with variable rates, most commonly reported as approximately 10% to 15%. High-level data on the combination of SABR with modern therapies are still lacking. At present, 19 clinical trials are ongoing, mainly focusing on combined modality therapies, radiotherapy prescription dose, and oligometastic disease. Conclusions and Relevance These findings suggest that spinal SABR may be an effective treatment option for well-selected patients with spinal metastases, achieving high rates of local tumor control with moderate rates of adverse effects. Optimal management should include review by a multidisciplinary care team. This review of stereotactic ablative radiotherapy for spinal metastases contextualizes decisions about optimal multidisciplinary management to help clinicians provide personalized high-quality care for these patients. Question What leads to decisions concerning stereotactic ablative radiotherapy application, patient selection, and personalized high-quality care for spinal metastases? Findings In this review of 5655 patients who underwent SABR for spinal metastases in 59 unique studies, optimal patient selection and stereotactic ablative radiotherapy were associated with high rates of local tumor control with moderate rates of adverse effects. Meaning This study suggests that spinal stereotactic ablative radiotherapy is an effective treatment option for well-selected patients with spinal metastases; future studies might explore the potential for broader applications of spinal stereotactic ablative radiotherapy and enhanced personalization of care.