Focused versus conventional radiotherapy in spinal oncology: is there any difference in fusion rates and pseudoarthrosis?

Abstract

IntroductionRadiotherapy is considered standard of care for adjuvant peri-operative treatment of many spinal tumors, including those with instrumented fusion. Unfortunately, radiation treatment has been linked to increased risk of pseudoarthrosis. Newerfocused radiotherapy strategies with enhanced conformalitycould offer improved fusion rates for these patients, but this has not been con rmed. MethodsWe performed a retrospective analysis of patients at three tertiary care academic institutions withprimary and secondary spinal malignancies that underwent resection, instrumented fusion, and peri-operative radiotherapy. Two board certi ed neuro-radiologists used theLenke fusion score to grade fusion status at6 and 12-months after surgery. Secondary outcomes includedclinical pseudoarthrosis, wound complications, and the effect of radiation timing, radiobiological dose delivered, the use of photons versus protons, tumor type, tumor location,and use of autograft on fusion outcomes. ResultsAfter reviewof 1252 spinal tumor patients, there were 60 patients with at least 6 months follow-up that were included in our analyses.Twenty-ve of these patients received focused radiotherapy,20 patients received conventional radiotherapy, and 15 patients were treated with protons. There was no signi cant difference between the groups for covariates such assmoking status,obesity, diabetes, intraoperative use of autograft, and use of peri-operative chemotherapy. There was a signi cantly higher rate of fusion for patients treated with focused radiotherapy compared to those treated with conventional radiotherapy at 6-months (64.0% versus 30.0%, Odds ratio: 4.15, p=0.036) and 12months (80.0% versus 42.1%, OR: 5.50, p=0.022). There was a signi cantly higher rate of clinical pseudoarthrosis in the conventional radiotherapy cohortcompared to patients in the focused radiotherapy cohort (19.1% versus 0%,p=0.037). There was no difference in fusion outcomes for any of the secondary outcomes except for use of autograft. The use o ntra-operative autograft was associated with an improved fusion at 12-months (66.7% versus 37.5%, OR: 3.33, p=0.043). ConclusionFocused radiotherapy may be associated withan improved rate of fusion and clinical pseudoarthrosis when compared to conventional radiation delivery strategiesin patients with spinal tumors.Use of autograft at the time of surgery may be associated with improved 12month fusion rates.Further large-scale prospective and randomized controlled studies are needed to better stratify the effects of radiation delivery modality in these patients.were to assess the impact of radiation timing, number of fractions, dose, use of photons or protons, and use of autograft on fusion rates.We hypothesize that fusion rates will be improved in those patients treated with focused radiation delivery strategies. Methods Patient PopulationThe authors performed a retrospective analysis of patients at each of the three sites of our tertiary care academic institution from January 2013 to October 2020. This study was approve...

Letter: Global Spinal Alignment Considerations in the Oncological Spine Population

“…9 Moreover, improvements in arthrodesis techniques and materials, focused radiotherapy, and minimally invasive approaches would be welcome avenues of further study and have existing evidence of improved outcomes in the spine tumor population. 10,11 Furthermore, as cancer patients' longevity and survival rates climb, cancer-related bone deterioration is becoming an increasingly prevalent force to contend with. 12 Bone health optimization describes the concerted effort to augment bone mineral density and osteoblastic activity in addition to correcting modifiable factors of bone health, thus enhancing spine healing after surgery.…”

“…9 Moreover, improvements in arthrodesis techniques and materials, focused radiotherapy, and minimally invasive approaches would be welcome avenues of further study and have existing evidence of improved outcomes in the spine tumor population. 10,11…”