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

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Abstract

Introduction

Radiotherapy 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. Newer focused radiotherapy strategies with enhanced conformality could offer improved fusion rates for these patients, but this has not been confirmed.

Methods

We performed a retrospective analysis of patients at three tertiary care academic institutions with primary and secondary spinal malignancies that underwent resection, instrumented fusion, and peri-operative radiotherapy. Two board certified neuro-radiologists used the Lenke fusion score to grade fusion status at 6 and 12-months after surgery. Secondary outcomes included clinical pseudoarthrosis, wound complications, the effect of radiation timing and radiobiological dose delivered, the use of photons versus protons, tumor type, tumor location, and use of autograft on fusion outcomes.

Results

After review of 1252 spinal tumor patients, there were 60 patients with at least 6 months follow-up that were included in our analyses. Twenty-five of these patients received focused radiotherapy, 20 patients received conventional radiotherapy, and 15 patients were treated with protons. There was no significant difference between the groups for covariates such as smoking status, obesity, diabetes, intraoperative use of autograft, and use of peri-operative chemotherapy. There was a significantly 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 12-months (80.0% versus 42.1%, OR: 5.50, p = 0.022). There was a significantly higher rate of clinical pseudoarthrosis in the conventional radiotherapy cohort compared 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 of intra-operative autograft was associated with an improved fusion at 12-months (66.7% versus 37.5%, OR: 3.33, p = 0.043).

Conclusion

Focused radiotherapy may be associated with an improved rate of fusion and clinical pseudoarthrosis when compared to conventional radiation delivery strategies in patients with spinal tumors. Use of autograft at the time of surgery may be associated with improved 12-month fusion rates. Further large-scale prospective and randomized controlled studies are needed to better stratify the effects of radiation delivery modality in these patients.

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Data availability

The datasets generated during and/or analyzed during the current study are not publicly available due to institutional policies for electronic medical record data but are available from the corresponding author on reasonable request.

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Funding

O.O.A. is supported by Neurosurgery Research and Education Foundation Funding, but this funding is not directly related to this project.

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Authors and Affiliations

  1. Department of Neurosurgery, Mayo Clinic, Jacksonville, FL, 32224, USA

    Oluwaseun O. Akinduro, Gaetano De Biase, Anshit Goyal, Alfredo Quiñones-Hinojosa & Kingsley Abode-Iyamah

  2. Department of Neurosurgery, Mayo Clinic, Phoenix, AZ, USA

    Jenna H. Meyer, Jamal McClendon Jr & Maziyar A. Kalani

  3. Department of Neuroradiology, Mayo Clinic, Jacksonville, FL, USA

    Sukhwinder J. S. Sandhu & Daniel F. Broderick

  4. Department of Radiation Oncology, Mayo Clinic, Rochester, MN, USA

    Roman O. Kowalchuk & Kenneth W. Merrell

  5. Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL, USA

    Daniel M. Trifiletti

  6. Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA

    Jason Sheehan

  7. Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, USA

    Sujay A. Vora

  8. Department of Neurosurgery, Mayo Clinic, Rochester, MN, USA

    Michelle J. Clarke & Mohamad Bydon

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  1. Oluwaseun O. Akinduro
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Contributions

OOA: writing manuscript, data collection, statistical analysis, reviewed final, GD: writing manuscript, data collection, statistical analysis AG: data collection, JM: data collection, SS: data collection, critically revised manuscript, RK: figure preparation, critically revised manuscript, DT: critically revised manuscript, JS: critically revised manuscript, KM: critically revised manuscript, SV: critically revised manuscript, DB: data collection, MC: critically revised manuscript, MB: critically revised manuscript, JM: critically revised manuscript, MK: critically revised manuscript, AQ: critically revised manuscript, KA: critically revised manuscript, study supervision.

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Correspondence to Oluwaseun O. Akinduro.

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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. IRB approval was obtained for this study.

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Akinduro, O.O., De Biase, G., Goyal, A. et al. Focused versus conventional radiotherapy in spinal oncology: is there any difference in fusion rates and pseudoarthrosis?. J Neurooncol 156, 329–339 (2022). https://doi.org/10.1007/s11060-021-03915-3

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