Patterns of epidural progression following postoperative spine stereotactic body radiotherapy: implications for clinical target volume delineation

Chan, Michael W.Y.; Thibault, Isabelle; Atenafu, Eshetu G.; Yu, Eugene; Cho, B C John; Létourneau, D.; Lee, Young Kyung; Yee, Albert; Fehlings, Michael G.; Sahgal, Arjun

doi:10.3171/2015.6.spine15294

Cited by 34 publications

(24 citation statements)

References 16 publications

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“…This limited the number of relevant studies to 11 19,21,23,25,29,48–53 (Supplemental Digital Content, Table 4, http://links.lww.com/BRS/B197). All studies were either prospective or retrospective series, none of which had control arms.…”

Section: Resultsmentioning

confidence: 99%

Stereotactic Body Radiotherapy for Spinal Metastases

Chang

Shin

Yamada

et al. 2016

Spine

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Study Design Systematic literature review. Objectives To summarize the risks of 3 key complications of stereotactic body radiotherapy (SBRT) for spinal metastases, that is, radiation myelopathy (RM), vertebral compression fracture (VCF), and epidural disease progression, and to discuss strategies for minimizing them. Summary of Background Data RM, VCF and epidural disease progression are now recognized as important risks following SBRT for spine metastases. It is unclear at this stage exactly how large these risks are and what strategies can be employed to minimize these risks. Methods A systematic review of the literature using MEDLINE and a review of the bibliographies of reviewed articles on SBRT for spinal metastases were conducted. Results The initial literature search revealed a total of 376 articles, of which 38 were pertinent to the study objectives. The risk of RM following SBRT was found to be dependent on the maximum dose to the spinal cord and estimated to be <5% if the recommended published thecal sac dose constraints are adhered to. The crude risk of VCF was 13.7% (range: 0.7%- 40.5%), and, on average, 45% were surgically salvaged. It has been shown that the risk of VCF is dependent on several anatomic and tumor-related factors including the SBRT dose per fraction. The crude risk of local failure at 1 year was 21.4% (range: 12%–27%) of which 67% (range: 38%–96%) occurred within the epidural space. The grade of epidural disease has been shown to be associated with the risk of local failure. Conclusion The risk of RM after spinal SBRT is low in particular if recommended dose metrics are adhered to. There is a significant risk of both VCF and epidural disease progression after spinal SBRT. These risks can potentially be minimized by identifying the risk factors for these complications, and performing careful radiotherapy and surgical planning.

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Section: Resultsmentioning

confidence: 99%

Stereotactic Body Radiotherapy for Spinal Metastases

Chang

Shin

Yamada

et al. 2016

Spine

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“…This is supported by recent patterns of failure analysis, which found that the location of preoperative epidural disease was more predictive of subsequent failure than the sites of residual epidural disease postoperatively. 4 Several controversies remain, including circumferential treatment of the epidural space as well as the appropriate margin in patients with soft tissue and paraspinal involvement. While future investigations will be critical in clarifying these concepts, we report many areas of consistency independently adapted by experienced spine oncology specialists driven by their clinical experience and outcomes.…”

Section: Discussionmentioning

confidence: 99%

Consensus guidelines for postoperative stereotactic body radiation therapy for spinal metastases: results of an international survey

Redmond¹,

Soltys

et al. 2017

SPI

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OBJECTIVE Although postoperative stereotactic body radiation therapy (SBRT) for spinal metastases is increasingly performed, few guidelines exist for this application. The purpose of this study is to develop consensus guidelines to promote safe and effective treatment for patients with spinal metastases. METHODS Fifteen radiation oncologists and 5 neurosurgeons, representing 19 centers in 4 countries and having a collective experience of more than 1300 postoperative spine SBRT cases, completed a 19-question survey about postoperative spine SBRT practice. Responses were defined as follows: 1) consensus: selected by ≥ 75% of respondents; 2) predominant: selected by 50% of respondents or more; and 3) controversial: no single response selected by a majority of respondents. RESULTS Consensus treatment indications included: radioresistant primary, 1–2 levels of adjacent disease, and previous radiation therapy. Contraindications included: involvement of more than 3 contiguous vertebral bodies, ASIA Grade A status (complete spinal cord injury without preservation of motor or sensory function), and postoperative Bilsky Grade 3 residual (cord compression without any CSF around the cord). For treatment planning, co-registration of the preoperative MRI and postoperative T1-weighted MRI (with or without gadolinium) and delineation of the cord on the T2-weighted MRI (and/or CT myelogram in cases of significant hardware artifact) were predominant. Consensus GTV (gross tumor volume) was the postoperative residual tumor based on MRI. Predominant CTV (clinical tumor volume) practice was to include the postoperative bed defined as the entire extent of preoperative tumor, the relevant anatomical compartment and any residual disease. Consensus was achieved with respect to not including the surgical hardware and incision in the CTV. PTV (planning tumor volume) expansion was controversial, ranging from 0 to 2 mm. The spinal cord avoidance structure was predominantly the true cord. Circumferential treatment of the epidural space and margin for paraspinal extension was controversial. Prescription doses and spinal cord tolerances based on clinical scenario, neurological compromise, and prior overlapping treatments were controversial, but reasonable ranges are presented. Fifty percent of those surveyed practiced an integrated boost to areas of residual tumor and density override for hardware within the beam path. Acceptable PTV coverage was controversial, but consensus was achieved with respect to compromising coverage to meet cord constraint and fractionation to improve coverage while meeting cord constraint. CONCLUSIONS The consensus by spinal radiosurgery experts suggests that postoperative SBRT is indicated for radioresistant primary lesions, disease confined to 1–2 vertebral levels, and/or prior overlapping radiotherapy. The GTV is the postoperative residual tumor, and the CTV is the postoperative bed defined as the entire extent of preoperative tumor and anatomical compartment plus residual disease. Hardware and scar do not need to be included in CTV. While predominant agreement was reached about treatment planning and definition of organs at risk, future investigation will be critical in better understanding areas of controversy, including whether circumferential treatment of the epidural space is necessary, management of paraspinal extension, and the optimal dose fractionation schedules.

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“…In the postoperative setting, practice may be guided by a recent detailed analysis of patterns of epidural progression following postoperative spine SBRT. 21 The authors analyzed 25 spine SBRT cases with preoperative epidural disease with subsequent epidural disease progression after postoperative SBRT. The location of epidural disease in this study was categorized based on dividing the vertebral anatomy into 6 sectors (anterior compartment: vertebral body and anterior epidural space, left and right pedicles and associated epidural space; posterior compartment: left and right transverse processes and laminae and associated epidural space, spinous process, and associated epidural space).…”

Section: Introductionmentioning

confidence: 99%

Spine Stereotactic Body Radiotherapy: Indications, Outcomes, and Points of Caution

Tseng

Eppinga

Charest-Morin

et al. 2017

Global Spine Journal

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Study Design:A broad narrative review.Objectives:The objective of this article is to provide a technical review of spine stereotactic body radiotherapy (SBRT) planning and delivery, indications for treatment, outcomes, complications, and the challenges of response assessment. The surgical approach to spinal metastases is discussed with an overview of emerging minimally invasive techniques.Methods:A comprehensive review of the literature was conducted on the techniques, outcomes, and developments in SBRT and surgery for spinal metastases.Results:The optimal management of patients with spinal metastases is complex and requires multidisciplinary assessment from an oncologic team that is familiar with the shifting paradigm as a consequence of evolving techniques in surgery and stereotactic radiation, as well as new developments in systemic agents. The Spinal Instability Neoplastic Score and the epidural spinal cord compression (Bilsky) grading system are useful tools that facilitate communication among oncologic team members and can direct management by providing a baseline assessment of risks prior to therapy. The combined multimodality approach with “separation surgery” followed by postoperative spine SBRT achieves thecal sac decompression, improves tumor control, and avoids complications that may be associated with more extensive surgery.Conclusion:Spine SBRT is a highly effective treatment that is capable of delivering ablative doses to the target while sparing the critical organs-at-risk, chiefly the critical neural tissues, within a short and manageable schedule. At the same time, surgery occupies an important role in select patients, particularly with the expanding availability and expertise in minimally invasive techniques. With rapid adoption of spine SBRT in centers outside of the academic setting, it is imperative for the practicing oncologist to understand the relevance and application of these evolving concepts.

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Patterns of epidural progression following postoperative spine stereotactic body radiotherapy: implications for clinical target volume delineation

Cited by 34 publications

References 16 publications

Stereotactic Body Radiotherapy for Spinal Metastases

Stereotactic Body Radiotherapy for Spinal Metastases

Consensus guidelines for postoperative stereotactic body radiation therapy for spinal metastases: results of an international survey

Spine Stereotactic Body Radiotherapy: Indications, Outcomes, and Points of Caution

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