Spinal Radiosurgery Research Articles

Stereotactic spine radiosurgery: Review of safety and efficacy with respect to dose and fractionation.

Background:Stereotactic body radiotherapy (SBRT) is an emerging treatment option for spinal metastases with demonstrated efficacy in the upfront, postoperative, and re-treatment settings, as well as for tumor histologies considered radioresistant. Uncertainty exists regarding the optimal dose and fractionation schedule, with single and multifraction regimens commonly utilized.Methods:A literature search of the PubMed and Medline databases was conducted to identify papers specific to spine SBRT and the effect of varying dose/fractionation regimens on outcomes. Bibliographies of relevant papers were searched for further references, and international spine SBRT experts were consulted.Results:Local control rates generally exceed 80% at 1 year, while high rates of pain control have been attained. There is insufficient evidence to suggest superiority of either single or multiple fraction regimens with respect to local control and pain control. Low rates of toxicity have been reported, assuming strict dose constraints are respected. Radiation myelopathy may be the most morbid toxicity, although the rates are low. The risk of vertebral compression fracture appears to be associated with higher doses per fraction such as those used in single-fraction regimens. The Spinal Instability Neoplastic Score should be considered when evaluating patients for spine SBRT, and prophylactic stabilisation may be warranted. Pain flare is a relatively common toxicity which may be mediated with prophylactic dexamethasone. Because of the treatment complexity and potentially serious toxicities, strict quality assurance should occur at the organizational, planning, dosimetric, and treatment delivery levels.Conclusion:Both single and multifraction regimens are safe and efficacious in spine SBRT for spinal metastases. There may be advantages to hypofractionated treatment over single-fraction regimens with respect to toxicity. Ongoing investigation is underway to define optimal dose and fractionation schedules.

Impact of cervicothoracic region stereotactic spine radiosurgery on adjacent organs at risk.

OBJECTIVE Stereotactic radiosurgery (SRS) of the spine is a conformal method of delivering a high radiation dose to a target in a single or few (usually ≤ 5) fractions with a sharp fall-off outside the target volume. Although efforts have been focused on evaluating spinal cord tolerance when treating spinal column metastases, no study has formally evaluated toxicity to the surrounding organs at risk (OAR), such as the brachial plexus or the oropharynx, when performing SRS in the cervicothoracic region. The aim of this study was to evaluate the radiation dosimetry and the acute and delayed toxicities of SRS on OAR in such patients. METHODS Fifty-six consecutive patients (60 procedures) with a cervicothoracic spine tumor involving segments within C5-T1 who were treated using single-fraction SRS between February 2006 and July 2014 were included in the study. Each patient underwent CT simulation and high-definition MRI before treatment. The clinical target volume and OAR were contoured on BrainScan and iPlan software after image fusion. Radiation toxicity was evaluated using the common toxicity criteria for adverse events and correlated to the radiation doses delivered to these regions. The incidence of vertebral body compression fracture (VCF) before and after SRS was evaluated also. RESULTS Metastatic lesions constituted the majority (n = 52 [93%]) of tumors treated with SRS. Each patient was treated with a median single prescription dose of 16 Gy to the target. The median percentage of tumor covered by SRS was 93% (maximum target dose 18.21 Gy). The brachial plexus received the highest mean maximum dose of 17 Gy, followed by the esophagus (13.8 Gy) and spinal cord (13 Gy). A total of 14 toxicities were encountered in 56 patients (25%) during the study period. Overall, 14% (n = 8) of the patients had Grade 1 toxicity, 9% (n = 5) had Grade 2 toxicity, 2% (n = 1) had Grade 3 toxicity, and none of the patients had Grade 4 or 5 toxicity. The most common (12%) toxicity was dysphagia/odynophagia, followed by axial spine pain flare or painful radiculopathy (9%). The maximum radiation dose to the brachial plexus showed a trend toward significance (p = 0.066) in patients with worsening post-SRS pain. De novo and progressive VCFs after SRS were noted in 3% (3 of 98) and 4% (4 of 98) of vertebral segments, respectively. CONCLUSIONS From the analysis, the current SRS doses used at the Cleveland Clinic seem safe and well tolerated at the cervicothoracic junction. These preliminary data provide tolerance benchmarks for OAR in this region. Because the effect of dose-escalation SRS strategies aimed at improving local tumor control needs to be balanced carefully with associated treatment-related toxicity on adjacent OAR, larger prospective studies using such approaches are needed.

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

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.

Feasibility of Simultaneous Integrated Boost (SIB) to Gross Disease in Spine Radiosurgery

Feasibility of Simultaneous Integrated Boost (SIB) to Gross Disease in Spine Radiosurgery

Clinical and Quality of Life Implications of Vertebral Compression Fracture Following Spine Radiosurgery

Clinical and Quality of Life Implications of Vertebral Compression Fracture Following Spine Radiosurgery

Spinal Stereotactic Radiosurgery: Comparison of Targeting the Gross Tumor Volume Alone Versus With the Adjacent Vertebral Segment

Spinal Stereotactic Radiosurgery: Comparison of Targeting the Gross Tumor Volume Alone Versus With the Adjacent Vertebral Segment

Recursive Partitioning Analysis Is Predictive of Overall Survival for Patients Undergoing Spine Radiosurgery for Spine Metastasis

Recursive Partitioning Analysis Is Predictive of Overall Survival for Patients Undergoing Spine Radiosurgery for Spine Metastasis

Impact of Swallowing on Doses Delivered to Spinal Cord in Cervical Spine Radiosurgery—Dynamic Volume Helical Shuttle Imaging Analysis

Spinal cord displacement happens when ever patient swallows in treatment position for head and neck cancers. Because of momentary breath hold during swallowing 4-D imaging is not ideal as it leads to sorting errors and image artifacts. Dynamic volume Helical shuttle (DVHS) imaging is continuous bidirectional scan with extended Z coverage, which enables us to delineate structures properly without any artifacts. The present study aims at evaluating the subtle dose deformations of spinal cord consequent to swallowing for patients undergoing cervical spine radiosurgery. Forty-two cervical spine metastases following rigid immobilization with S-Board underwent thin slice CT imaging on 128 slice CT scanner and post-contrast myelographic MR imaging (Axial T2 FSE, FS, and CISS sequence). With regards to CT imaging, all patients underwent a 10 second static CT scan (no swallowing) and 3 mts - DVHS imaging (with effortful swallowing). For DVHS, image data for single patient was acquired during voluntary effortful swallowing act (once in 20 sec) at 2 alternating table positions with the table shuttling back and forth. Nearly 2,000 images/per pt. were reformatted using Dynamic Pitch Cone Beam Reconstruction for 15 passes @ 2.5 mm thickness and cine looped to quantify the range of motion. Following target and thecal sac localization on fused CT-MR scan, a median dose of 18 Gy was planned using single VMAT arc on static scan dataset, which is then deformably dose warped on the extreme passes of DVHS deglutition dataset. The registration accuracy was quality assured using reg-refine and reg-reveal tools using alignment locks. Deglutition-induced GTV and Spinal cord displacements were quantified based on position change during deglutition relative to pre-swallow structure location in S-I, A-P, and lateral directions. The dose variations consequent to deglutition were analyzed and changes greater than 0.5 Gy reported as percent change (normalized to prescription dose) were considered potentially significant. Deglutition-induced maximal PTV displacements ranged from 2 mm to 5 mm with mean and standard deviation of 1.5 +/- 2, 1.70 +/- 1.51, 2.25 +/- 1.2, and 2.2 +/- 1.7 mm in the A, P, I, and S directions, respectively. The SC displacement ranged from 2.8 mm +/- 0.1 mm, 2.2 mm +/- 1.4 mm in A-P direction. Upon dosimetric analysis on extreme passes of DVHS dataset 35 of 42 patients showed that 96% of the prescribed dose would still be delivered to the tumor even if the tumor partly vacated the PTV during the act of swallowing. For the remaining 7 patients (frequent swallowers), the target coverage reached to around 92%. For non-spinous process target, a 2 mm shift increased thecal dose up to 100 cGy. The median accumulated doses delivered in spinal cord were high in frequent swallowers. This is the first study reported in literature using DHVS to analyze motion in cervical spine radiosurgery. FFF technology with actual BOT around 2 mts would be preferred as it mitigates impact of swallowing on dose deformations.

Spine Stereotactic Body Radiotherapy Outcomes in Patients with Concurrent Brain Metastases.

Objectives: Stereotactic body radiotherapy (SBRT) is an emerging technique for maximizing tumor and pain control in selected patients with spinal metastases. Outcomes for those with concurrent brain metastases (CBM) have not been well-described previously. The goal of this study was to compare outcomes for patients with or without CBM treated with spine SBRT.Methods: Records of all patients treated with SBRT for spine metastases at our institution from January 2008 to January 2014 were reviewed. Chi-square analyses and the Mann-Whitney test were used to assess the association of CBM (defined as brain metastasis present prior to or at the time of spinal SBRT) with potential covariates. The log-rank test and Cox proportional hazards regression were used to evaluate the impact of CBM on overall survival and local control from the time of the first course of spine SBRT.Results: Seventy-eight patients and a total of 86 SBRT lesions were treated. Median patient age was 60 years (range: 38-84 years); 28.2% had radioresistant histologies. A single fraction was used in 91.0% of treatments. One-year local control was 89.4%, and one-year overall survival was 45.8%. A total of 19 patients (24.4%) had CBM. Among these CBM patients, 18 (94.7%) underwent intracranial radiosurgery and nine (47.4%) were diagnosed synchronously with their spine metastases. Local control was not significantly different between patients with or without CBM on univariable (median: 58 months vs. not reached, p = 0.53) or multivariable analyses (HR 0.52, 95% CI 0.06-4.33). Overall survival was also not significantly different between patients with or without CBM on univariable (median: 7 vs. 11 months, log-rank p = 0.12) or multivariable analyses (HR 1.62, 95% CI 0.87-3.03).Conclusions: Patients with CBM do not appear to have a statistically significant detriment in clinical outcomes, suggesting that CBM should not necessarily be considered a contraindication for spine SBRT. Although our study is limited by significant heterogeneity in tumor type within our series, future work should focus on the development of reliable survival prognosticators for patients undergoing spinal radiosurgery. Nearly half of the patients with CBM were diagnosed synchronously with their spine metastases, emphasizing the usefulness of obtaining a brain MRI for complete staging prior to spine SBRT.

Pushing the limits of the Leksell stereotactic frame for spinal lesions up to C3: fixation at the maxilla.

Spinal radiosurgery is not considered in the domain of traditional Gamma Knife radiosurgery (GKRS) setup. The major obstacles in GKRS for upper cervical spine lesions remain in difficulty of frame fixation, avoiding collision and maintaining the integrity of the relative position of the lesion from image acquisition to treatment. The supraorbital margin remains the standard lowest fixation point for Leksell stereotactic frame. We describe fixation at the maxilla to target and treat upper cervical spine lesions (up to C3 vertebra) with measures to ensure cervical immobilisation and precision of the GKRS treatment. We have treated two patients at the upper cervical spine up to C3 vertebra by fixing anterior pillars of the Leksell stereotactic frame at the maxilla. To ensure cervical immobilisation and precision of treatment, the neck was immobilised with a Philadelphia collar. The relative position between the head and sternum with the couch from image acquisition to the radiation delivery was kept constant. Docking angle was kept neutral (90 degrees) throughout the treatment (from image acquisition to actual treatment). The maxilla is a potential alternative for stereotactic frame fixation. Measures to ensure cervical immobilisation with lower-down frame position permits treatment of lesions as low as C3 vertebra.

Variability in spine radiosurgery treatment planning - results of an international multi-institutional study.

BackgroundThe aim of this study was to quantify the variability in spinal radiosurgery (SRS) planning practices between five international institutions, all member of the Elekta Spine Radiosurgery Research Consortium.MethodsFour institutions provided one representative patient case each consisting of the medical history, CT and MR imaging. A step-wise planning approach was used where, after each planning step a consensus was generated that formed the basis for the next planning step. This allowed independent analysis of all planning steps of CT-MR image registration, GTV definition, CTV definition, PTV definition and SRS treatment planning. In addition, each institution generated one additional SRS plan for each case based on intra-institutional image registration and contouring, independent of consensus results.ResultsAveraged over the four cases, image registration variability ranged between translational 1.1 mm and 2.4 mm and rotational 1.1° and 2.0° in all three directions. GTV delineation variability was 1.5 mm in axial and 1.6 mm in longitudinal direction averaged for the four cases. CTV delineation variability was 0.8 mm in axial and 1.2 mm in longitudinal direction. CTV-to-PTV margins ranged between 0 mm and 2 mm according to institutional protocol. Delineation variability was 1 mm in axial directions for the spinal cord. Average PTV coverage for a single fraction18 Gy prescription was 87 ± 5 %; Dmin to the PTV was 7.5 ± 1.8 Gy averaged over all cases and institutions. Average Dmax to the PRV_SC (spinal cord + 1 mm) was 10.5 ± 1.6 Gy and the average Paddick conformity index was 0.69 ± 0.06.ConclusionsResults of this study reflect the variability in current practice of spine radiosurgery in large and highly experienced academic centers. Despite close methodical agreement in the daily workflow, clinically significant variability in all steps of the treatment planning process was demonstrated. This may translate into differences in patient clinical outcome and highlights the need for consensus and established delineation and planning criteria.

Volumetric Modulated Arc Therapy for Spine Radiosurgery: Superior Treatment Planning and Delivery Compared to Static Beam Intensity Modulated Radiotherapy.

Purpose. Spine stereotactic radiosurgery (SRS) delivers an accurate and efficient high radiation dose to vertebral metastases in 1–5 fractions. We aimed to compare volumetric modulated arc therapy (VMAT) to static beam intensity modulated radiotherapy (IMRT) for spine SRS. Methods and Materials. Ten spine lesions of previously treated SRS patients were planned retrospectively using both IMRT and VMAT with a prescribed dose of 16 Gy to 100% of the planning target volume (PTV). The plans were compared for conformity, homogeneity, treatment delivery time, and safety (spinal cord dose). Results. All evaluated parameters favored the VMAT plan over the IMRT plans. D min in the IMRT was significantly lower than in the VMAT plan (7.65 Gy/10.88 Gy, p < 0.001), the Dice Similarity Coefficient (DSC) was found to be significantly better for the VMAT plans compared to the IMRT plans (0.77/0.58, resp., p value < 0.01), and an almost 50% reduction in the net treatment time was calculated for the VMAT compared to the IMRT plans (6.73 min/12.96 min, p < 0.001). Conclusions. In our report, VMAT provides better conformity, homogeneity, and safety profile. The shorter treatment time is a major advantage and not only provides convenience to the painful patient but also contributes to the precision of this high dose radiation therapy.

Can the spinal instability neoplastic score prior to spinal radiosurgery predict compression fractures following stereotactic spinal radiosurgery for metastatic spinal tumor?: a post hoc analysis of prospective phase II single-institution trials

The aim of this study was to determine the predictability of vertebral compression fracture (VCF) development applying the spinal instability neoplastic score (SINS) prior to delivery of stereotactic spinal radiosurgery (SSRS) for spinal metastases. From two prospective cohorts of SSRS for spinal metastases, we selected patients with a low degree of cord compression or cauda equine from C3 to S1 and analyzed 79 patients enrolled according to binary SINS criteria. The primary endpoint was the development of a de novo VCF or progression of an existing fracture after SSRS. We identified 32 fractures (40.5%): 19 de novo and 13 progressive. The mean time to fracture after SSRT was 3.3 months (range, 0.4-34.1 months). In 41 patients with low SINS (0-6), 7 patients (17.1%) developed a fracture after SSRS. In 38 patients with high SINS (7-12), 25 (65.8%) developed a fracture. Among the 32 fractures, 15 were symptomatic. Patients with high SINS were more likely to experience symptomatic fractures (31.6%) than were patients with lower SINS (7.4%). On univariate and multivariate analysis, 24-month fracture-free rates were 78.7 and 33.7% in low and high SINS group, respectively and high SINS was found to be a significant risk factor for VCFs and symptomatic fractures (respectively, HR 5.6, p = 0.04; HR 5.3, p = 0.01). SINS is a useful tool for predicting the development of VCF after SSRS for spinal metastases. Prophylactic cement augmentation should not be considered for patients with lower SINS, since the risk of fracture is low.

Clinical outcome of vertebral compression fracture after single fraction spine radiosurgery for spinal metastases.

Vertebral compression fracture (VCF) occurs after stereotactic body radiation therapy (SBRT) for spine metastasis. Recently, single fraction radiosurgery (sfSRS) is used more frequently. The aim of this study is to determine the clinical outcome of VCF after sfSRS. Spinal instability neoplastic score (SINS) criteria were used to retrospectively score 143 consecutive vertebral segments in 79 patients treated with SRS. Follow-up MRI, pain, and neurologic assessments obtained every 3-6months. Pain also scored at 7, 14, and 30days after sfSRS. Follow up was 16±18months ±SD, range 3-78. Long-term radiographic control occurred in 94% of cases. Pain improvement resulted within 7days in 100% of cases with severe pain and sustained long-term in 95%. VCF occurred in 21% of segments: 30% were de novo VCF. The overall 1year fracture free probability (1yFFP) was 76%. Pre-existing VCF resulted in higher probability to progress: 1yFFP 90 versus 60%. Symptoms presented in 6% of cases with de novo VCF and 39% with progressive. The former were treated with vertebral augmentation (VA), the latter with open surgery. Surgery/VA prior to SRS did not change risk of progressive VCF. Univariate but not multivariate analysis identified histology (colorectal), pre-existing VCF, and pain (severe) as significant predictors of VCF. In conclusion, sfSRS compares favourably to SBRT for radiographic and pain control with similar VCF risk. Patients with pre-existing VCF have a higher probability to progress, become symptomatic, and require surgery. These results may help discussing risk and benefits with patients undergoing sfSRS for spinal metastasis and developing new treatment algorithms.

Quantitative Evaluation of Local Control and Wound Healing Following Surgery and Stereotactic Spine Radiosurgery for Spine Tumors

The present study evaluated the optimal measuring criteria to assess spinal tumor response to surgery followed by stereotactic spine radiosurgery (SRS) and reports the local control and wound complication rates following combined multimodality treatment. Prospectively collected patient information was retrospectively reviewed to identify patients treated with spine surgery followed by SRS. Tumor sizes and volumetric assessment were formally measured. Local control status was defined according to World Health Organization (WHO, bidimensional), RECIST (unidimensional), or volumetric size change. Statistical comparative assessments of tumor measurements were performed. Twenty-two patients were eligible for evaluation after having undergone surgery followed by single-fraction SRS within a 2-month period. Seventeen had follow-up magnetic resonance imaging (MRI) with a mean patient follow-up of 12.59 months (range 3-36 months). None developed wound complication after radiation therapy (95% lower confidence bound 13%). Two patients had clinical recurrence while 15 of 17 achieved local control (88.3%). A test of marginal homogeneity for RECIST versus WHO was not statistically significant, P = 1.0 suggesting similar response classifications with both systems. Spearman correlations among 1) volumetric assessment, 2) bidimensional size, and 3) unidimensional size were significant for all groups (P < 0.05). High local control rates can be achieved with surgery followed by SRS. Further, adjuvant SRS following spine tumor surgery delivers less radiation to the wound than conventional radiation and thus potentially reduces wound complications. Unidimensional, bidimensional, and volumetric tumor assessments demonstrate similar results. Hence the use of the simpler RECIST criteria is suitable and appropriate for evaluating the response to treatment after spine radiosurgery.

Variability of Spinal Cord Definition Using MR T2 Versus CT Myelography for Spine Radiosurgery

Variability of Spinal Cord Definition Using MR T2 Versus CT Myelography for Spine Radiosurgery

Efficacy of Spine Radiosurgery for Oligometastatic Spine Disease: A Large Institutional Experience

Efficacy of Spine Radiosurgery for Oligometastatic Spine Disease: A Large Institutional Experience

Spine Radiosurgery for the Treatment of Spine Metastases and Primary Spine Tumors: A Large Institutional Series

Spine Radiosurgery for the Treatment of Spine Metastases and Primary Spine Tumors: A Large Institutional Series

Dose Volume Response Relationship for Brain Metastases Treated With Single Fraction Linear Accelerator Based Radiosurgery

Evaluation of Postoperative Spine Radiosurgery Following Separation Surgery for Spinal Metastases With High Grade Epidural Spinal Cord Compression K.D. Kelley, R. Racareanu, J.B. Cohen, A. Sharma, M. Marrero, E. Gogineni, A. Latefi, and M. Ghaly; North Shore Long Island Jewish Medical Center, Lake Success, NY, North Shore-LIJ Health System, Lake Success, NY, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY

Spine Radiosurgery for the Treatment of Sacral Spine Metastases

Spine Radiosurgery for the Treatment of Sacral Spine Metastases