Spine Stereotactic Body Radiotherapy Research Articles

SU-E-T-355: A Comparative Study of Robotic and Linac-Based Stereotactitc Body Radiation Therapy for Lumbar Spinal Tumors

Purpose: Dosimetrically compare CyberKnife (CK) and linac-based (LB) stereotactic body radiotherapy (SBRT) plans for lumbar spine. Methods: Ten patient plans with lumbar spine tumors treated with CK were selected and retrospectively optimized using three techniques: CK, volumetric modulated arc (VMAT, three arcs), and 9-field-intensity modulated radiotherapy (IMRT). For the LB plans, the target volume was expanded by 1mm to accommodate additional uncertainty in patient positioning. All plans were optimized to a prescription dose of 27Gy in 3 fractions covering 90% of the PTV. If the dose constraints to the cauda equina (cauda) were not met, the prescription dose was lowered to 24Gy. Parameters evaluated included Paddick Conformity-Index (CI) and Gradient-Index (GI). A two-tailed paired t-test was used to establish statistically significant differences in cauda doses. Results: Target volumes for LB plans were on average 38% larger. In terms of the indices, the closer the index values to unity the steeper the dose falloff and the higher the dose conformity to the target. The results showed that LB plans were in general statistically superior to CK plans. The IMRT plan showed the best average gradient index of 2.995, with VMAT and CK GI values of 3.699 and 5.476, respectively. Similarly, themore » same trend occurs with the average CI results: 0.821, 0.814, and 0.758, corresponding to IMRT, VMAT, and CK. Notably, in one CK plan the target dose was reduced to 24Gy to meet cauda constraints. Additionally, there was a statistically significant dose difference for the cauda between the CK and LB plans. Conclusion: This study demonstrates that LB plans for lumbar spine SBRT can be as effective or even better than CK plans. Despite the expansion of the target volume, the LB plans did not demonstrate dosimetric inferiority. The LB plans Resultin 2-to-3 fold decrease of treatment time.« less

Spine Stereotactic Body Radiation Therapy Residual Setup Errors and Intra-Fraction Motion Using the Stereotactic X-Ray Image Guidance Verification System.

PurposeTo determine the precision of our institution’s current immobilization devices for spine SBRT, ultimately leading to recommendations for appropriate planning margins.MethodsWe identified 12 patients (25 treatments) with spinal metastasis treated with spine Stereotactic Body Radiation Therapy (SBRT). The Body-FIX system was used as immobilization device for thoracic (T) and lumbar (L) spine lesions. The head and shoulder mask system was used as immobilization device for cervical (C) spine lesions. Initial patient setup used the infrared positioning system with body markers. Stereotactic X-ray imaging was then performed and correction was made if the initial setup error exceeded predetermined institutional tolerances, 1.5 mm for translation and 2° for rotation. Three additional sets of verification X-rays were obtained pre-, mid-, and post-treatment for all treatments.ResultsIntrafraction motion regardless of immobilization technique was found to be 1.28 ± 0.57 mm. The mean and standard deviation of the variances along each direction were as follows: Superior-inferior, 0.56 ± 0.39 mm and 0.77 ± 0.52 mm, (p = 0.25); Anterior-posterior, 0.57 ± 0.43 mm and 1.14 ± 0.61 mm, (p = 0.01); Left-right, 0.48 ± 0.34 mm and 0.74 ± 0.40 mm, (p = 0.09) respectively. There was a significantly greater difference in the average 3D variance of the BodyFIX as compared to the head and shoulder mask immobilization system, 1.04 ± 0.46 mm and 1.71 ± 0.52 mm; (p = 0.003) respectively.ConclusionsOverall, our institution’s image guidance system using stereotactic X-ray imaging verification provides acceptable localization accuracy as previously defined in the literature. We observed a greater intrafraction motion for the head and shoulder mask as compared with the BodyFIX immobilization system, which may be a result of greater C-spine mobility and/or the suboptimal mask immobilization. Thus, better immobilization techniques for C-spine SBRT are needed to reduce setup error and intrafraction motion. We are currently exploring alternative C-spine immobilization techniques to improve set up accuracy and decrease intrafraction motion during treatment.

EP-1407: Multi-institutional planning study for spine stereotactic body radiation therapy with cyberknife in Japan

EP-1407: Multi-institutional planning study for spine stereotactic body radiation therapy with cyberknife in Japan

Dosimetric Comparison of Volumetric Modulated Arc Therapy and Helical Tomotherapy for Spine Stereotactic Body Radiation Therapy

The successful delivery of spine stereotactic body radiation therapy (SBRT) requires a delicate balance of coverage, conformality and spinal cord sparing. Volumetric modulated arc therapy (VMAT) and helical tomotherapy (Tomo) are rotation-based radiation therapy techniques with known dosimetric advantages in achieving these goals in other disease sites. However, these treatments have never been compared in spine SBRT. Thus, we evaluated coverage, conformality/heterogeneity, and spinal cord sparing in 10 spine SBRT cases planned using VMAT and Tomo.

Spinal Cord Tolerance Specific to Re-irradiation Spine Stereotactic Body Radiation Therapy (SBRT) Following at Least 2 Courses of Prior Radiation

Spinal Cord Tolerance Specific to Re-irradiation Spine Stereotactic Body Radiation Therapy (SBRT) Following at Least 2 Courses of Prior Radiation

Incidence and Risk Factors for Vertebral Compression Fractures From Spine Stereotactic Body Radiation Therapy: Results of a Large Institutional Series

There is a paucity of data regarding the incidence of and risk factors associated with the development of vertebral compression fractures (VCF) post-spine stereotactic body radiation therapy (sSBRT). Patients who underwent sSBRT, typically for spine metastases, were included in an IRB-approved database. Gender, consult KPS, epidural disease, thecal sac compression, histology, spine tumor location, VCF, pre-existing VCF, and dosimetric factors (prescription dose, target volume, maximum target dose) were retrospectively collected. Pain relief post-sSBRT was prospectively collected using the Brief Pain Inventory. These factors were correlated to the development of new VCF or the progression of a pre-existing VCF. Survival was calculated using Kaplan-Meier analysis and Cox proportional hazards modeling was utilized to evaluate the association between the clinical factors and the occurrence of VCF. A total of 507 treatments (348 patients) were included in this study. Median KPS, follow-up, and prescription dose were 80 (range, 30-100), 8 months (range, 1-72), and 15 Gy in one fraction (range, 7-18), respectively. Fifty-seven percent of patients were prior smokers whereas only 9% were actively smoking. The reasons for treatment were pain (73%), pain and neurological deficit (13%), asymptomatic (10%), and only neurological deficit (3%). Renal cell carcinoma (24%), lung cancer (14%), and breast cancer (11%) were the most common histologies. Multiple myeloma accounted for 7.3% of treatments. Fifty-nine percent, 32%, and 9% of tumors were located in the cervical/thoracic, lumbar, and sacral spine, respectively. Some patients received prior external beam radiation therapy (26%), sSBRT (4%), surgery (21%) and kyphoplasty (5%). Pre-existing VCF was present in 31% of treatments. Actuarial survival, radiographic control and pain control at 6/12 months were 71%/55%, 74%/64% and 82%/ 75%, respectively. Progression of a pre-existing VCF or development of a new VCF occurred in 15% of treatments. Univariate analysis demonstrated that prior smoking (HR 1.7, p = 0.04), current smoking (HR 1.9, p = 0.03), pain as a reason for treatment (HR 15.4, p < 0.01), lumbar vs sacral spine (HR 4.8, p = 0.03) and pre-existing VCF (HR 5.7, p < 0.01) were predictors of VCF. Multivariate analysis showed that only pre-existing VCF (HR 5.6, p < 0.01) and pain as a reason for treatment (HR 14.9, p < 0.01) were significant predictors of VCF. In our series of over 500 treatments, the incidence of VCF was low (15%). Important predictors of VCF were pre-existing VCF, pain as the reason for treatment, smoking, as well as lumbar spine location. This data shows that the rate of VCF is acceptable at sSBRT doses up to 16 Gy in one fraction.

A Pilot Study on Spine Stereotactic Body Radiation Therapy Residual Setup Errors and Intrafraction Motion Using Stereotactic X-ray Image Guidance Verification System

A Pilot Study on Spine Stereotactic Body Radiation Therapy Residual Setup Errors and Intrafraction Motion Using Stereotactic X-ray Image Guidance Verification System

A Dosimetric Evaluation of Target Coverage as a Predictor of Local Failure Following Stereotactic Body Radiation Therapy for Spinal Tumors

To perform a dosimetric analysis of target coverage and determine parameters predictive for local failure (LF) in patients undergoing spinal stereotactic body radiation therapy (sSBRT).Materials and Methods: Sixty-seven spinal tumors in 59 patients were treated with image-guided linac-based sSBRT from 2008-2012. Median prescription dose was 18Gy (8-35) delivered in 1-5 fractions (87% single-fraction). Prescription dose was targeted to cover ≥ 80% of PTV within spinal cord (SC) dose constraints (9/11Gy to 0.1cc SC/SC+2mm). Twelve tumors had local failure (LF, median time-to-failure 3.7 months) and were compared to 14 tumors with >1-year follow-up and local control (LC). Univariate and multivariate analyses were performed to determine parameters predictive of LF. Median follow-up was 7.4 months and 24.7 months for LF and LC, respectively. Post-SBRT, 42% of LF patients had neurological symptoms due to tumor progression. No patients developed post-SBRT myelopathy. Pre-treatment PTV volumes were not statistically different (median/mean/range 61.8/74.5/19.9-206.4cc for LF vs 39.4/47.1/10.3-119.7cc for LC; p=0.13). LF tumors had larger volumes receiving <80% of prescription dose (5.2cc vs 1.9cc, p=0.02) and larger overlap volume between GTV/SC within 2 and 3mm (p=0.01/p=0.007). LF tumors had lower GTV minimum dose (5.6 vs 8.5Gy, p=0.001) and smaller GTV to SC distance (0.06 vs 0.19mm, p=0.049). Maximum SC doses were not statistically different (6.4Gy LC vs 9.2Gy LF, p=0.33). GTV minimum dose was predictive of LF, with a trend for overlapping GTV/SC volume within 2mm. Minimum GTV dose, PTV volume receiving <80% prescription dose, smaller GTV-SC distance, and large overlapping volume of PTV/SC are predictive of LF after SBRT. Given the absence of SC toxicity but neurological progression upon LF, less conservative SC constraints should be considered.

Surgical resection of epidural disease improves local control following postoperative spine stereotactic body radiotherapy

Spine stereotactic body radiotherapy (SBRT) is increasingly being applied to the postoperative spine metastases patient. Our aim was to identify clinical and dosimetric predictors of local control (LC) and survival. Eighty patients treated between October 2008 and February 2012 with postoperative SBRT were identified from our prospective database and retrospectively reviewed. The median follow-up was 8.3 months. Thirty-five patients (44%) were treated with 18-26 Gy in 1 or 2 fractions, and 45 patients (56%) with 18-40 Gy in 3-5 fractions. Twenty-one local failures (26%) were observed, and the 1-year LC and overall survival (OS) rates were 84% and 64%, respectively. The most common site of failure was within the epidural space (15/21, 71%). Multivariate proportional hazards analysis identified systemic therapy post-SBRT as the only significant predictor of OS (P = .02) and treatment with 18-26 Gy/1 or 2 fractions (P = .02) and a postoperative epidural disease grade of 0 or 1 (0, no epidural disease; 1, epidural disease that compresses dura only, P = .003) as significant predictors of LC. Subset analysis for only those patients (n = 48/80) with high-grade preoperative epidural disease (cord deformed) indicated significantly greater LC rates when surgically downgraded to 0/1 vs 2 (P = .0009). Postoperative SBRT with high total doses ranging from 18 to 26 Gy delivered in 1-2 fractions predicted superior LC, as did postoperative epidural grade.

Monte Carlo calculation of dose distributions in oligometastatic patients planned for spine stereotactic ablative radiotherapy

Dosimetric consequences of plans optimized using the analytical anisotropic algorithm (AAA) implemented in the Varian Eclipse treatment planning system for spine stereotactic body radiotherapy were evaluated by re-calculating with BEAMnrc/DOSXYZnrc Monte Carlo. Six patients with spinal vertebral metastases were planned using volumetric modulated arc therapy. The planning goal was to cover at least 80% of the planning target volume with a prescribed dose of 35 Gy in five fractions. Tissue heterogeneity-corrected AAA dose distributions for the planning target volume and spinal canal planning organ-at-risk volume were compared against those obtained from Monte Carlo. The results showed that the AAA overestimated planning target volume coverage with the prescribed dose by up to 13.5% (mean 8.3% +/− 3.2%) when compared to Monte Carlo simulations. Maximum dose to spinal canal planning organ-at-risk volume calculated with Monte Carlo was consistently smaller than calculated with the treatment planning system and remained under spinal cord dose tolerance. Differences in dose distribution appear to be related to the dosimetric effects of accounting for body composition in Monte Carlo simulations. In contrast, the treatment planning system assumes that all tissues are water-equivalent in their composition and only differ in their electron density.

Vertebral Compression Fracture After Spine Stereotactic Body Radiotherapy: A Multi-Institutional Analysis With a Focus on Radiation Dose and the Spinal Instability Neoplastic Score

Vertebral compression fracture (VCF) is increasingly recognized as an adverse event after spine stereotactic body radiotherapy (SBRT). We report a multi-institutional study aimed at clarifying the risk and predictive factors associated with VCF. A total of 252 patients with 410 spinal segments treated with SBRT were included. The primary outcome was the development of VCF (a new VCF or progression of a baseline VCF). In addition to various patient-, treatment-, and tumor-specific factors, the Spinal Instability Neoplastic Scoring (SINS) system was applied to determine predictive value. The median follow-up was 11.5 months (range, 0.03 to 113 months). The median and mean overall survival rates were 16 and 26 months, respectively. We observed 57 fractures (57 of 410, 14%), with 47% (27 of 57) new fractures and 53% (30 of 57) fracture progression. The median time to VCF was 2.46 months (range, 0.03 to 43.01 months), and 65% occurred within the first 4 months. The 1- and 2-year cumulative incidences of fracture were 12.35% and 13.49%, respectively. Multivariable analysis identified dose per fraction (greatest risk for ≥ 24 Gy v 20 to 23 Gy v ≤ 19 Gy), in addition to three of the six original SINS criteria: baseline VCF, lytic tumor, and spinal deformity, as significant predictors of VCF. Caution must be observed when treating with ≥ 20 Gy/fraction, in particular, for patients with lytic tumor, spinal misalignment, and a baseline VCF. Frequent short-term follow-up is required, as nearly two thirds of all VCF occurred within the first 4 months. We also conclude that SINS may have utility in predicting patients at high risk of SBRT-induced VCF.

Repeat stereotactic body radiotherapy for recurrent spinal tumors is feasible with accurate assessment of cumulative spinal cord dose

Objective This study aims to report our initial clinical experience using quantitative dosimetric data comparing two methods for estimating cumulative dose from two different planning CTs to the spinal cord or cauda equina (SC/CE) for repeat spine stereotactic body radiotherapy (sSBRT) of patients with marginal recurrence after initial sSBRT.

Digital tomosynthesis for verifying spine position during radiotherapy: a phantom study

Monitoring the stability of patient position is essential during high-precision radiotherapy such as spine stereotactic body radiotherapy (SBRT). We evaluated the combination of digital tomosynthesis (DTS) and triangulation for spine position detection, using non-clinical DTS software and an anthropomorphic pelvic phantom that includes a bone-like spine structure. Kilovoltage cone beam CT projection images over 2–16° gantry rotation were used to generate single slice DTS images. Each DTS slice was registered to a digitally reconstructed DTS derived from the planning CT scan to determine 2D shifts between actual phantom and treatment plan position. Two or more DTS registrations, central axes 4–22° apart, were triangulated to determine the 3D phantom position. Using sequentially generated DTS images, the phantom position can be updated every degree with a small latency of DTS and triangulation angle. The precision of position determination was investigated as function of DTS and triangulation angle. To mimic the scenario of spine SBRT, the effect on the standard deviation of megavoltage radiation delivery during kV image acquisition was tested. In addition, the ability of the system to detect different types of movement was investigated for a variety of small sudden and gradual movements during kV image acquisition.

Spine stereotactic body radiotherapy – Experience from Cleveland Clinic

Spine stereotactic body radiotherapy – Experience from Cleveland Clinic

SU‐E‐T‐418: Dynamic Arc Technique Improves Delivery Accuracy of Stereotactic Body Radiation Therapy (SBRT) for Spine

Purpose: To investigate whether delivery accuracy can be improved with volumetric intensity modulated arc (VMAT), a hybrid dynamic arc therapy (HA) with fixed beam IMRT when compared to fixed beam IMRT alone for spine SBRT. Methods: Ten spine patients who underwent SBRT treatment using fixed beam IMRT were randomly chosen from an IRB approved registry. All cases were replanned with VMAT and HA techniques. The VMAT plans were created using the Pinnacle 9.0 with four 120 degree coplanar arcs and 120 segments. HA plans and clinical IMRT plans were created from Brainlab iplan. All HA plans used one 360 dynamic arc and 5–7 IMRT fixed beams, consisting 150–180 segments. All clinically IMRT plans used 7–9 fixed IMRT beams with 200–250 segments. All VMAT and HA plans were similar or better than clinical IMRT plans, meeting clinical objectives. All thirty plans were delivered with the same linear accelerator and measured with a 2D ion chamber array. The gamma index (GI) (3mm/3% and 2mm/2%) was used to test the delivery accuracy for each plan. Results: For the three delivery techniques, VMAT, HA, and IMRT, the average GI of 3mm/3% were 98.9±0.6%, 96.5±2.7%, and 92.6±1.1%, respectively. The average GI of 2mm/2% were 92.3±2.4%, 90.4±2.1%, and 82.0±2.2%, respectively. There is no significant difference on delivery accuracy between the VMAT plans and HA plans(P =0.09 for GI (3mm/3%) and P=0.229 for GI(2mm/2%)). There is a significant difference (P&lt;0.05) on delivery accuracy between VMAT (or HA) and IMRT plans based on GI of 3mm/3% and 2mm/2% criteria. Conclusions Dynamic arc techniques improve delivery accuracy of stereotactic body radiation therapy for the spinal lesions. VMAT or HA is a better choice than fixed beam IMRT with improved delivery accuracy.

SU‐E‐T‐675: The Effect of Diaphragm Motion to Dose Calculation During Stereotactic Body Radiotherapy (SBRT) Treatment of Spine Lesions Located at the Superior‐Inferior Level of the Diaphragm

Purpose: To investigate the effect of respiratory motion on dose calculation during stereotactic body radiotherapy (SBRT) treatment of spine lesions located at the level of diaphragm. Methods: Helical and four‐dimensional (4D) CT data sets of four patients were used for this study. The 4D sets were binned using 10 respiratory phases (0%–90%) and an average CT was reconstructed from the 4D CT sets. The recorded diaphragm motions were 0.8cm, 1.2cm, 1.4cm, and 1.7cm respectively. The helical CT might represent an arbitrary respiratory phase. The 0% and 50 % CT represent the inhale and exhale phases respectively. One vertebral body (PTV) and the thecal sac at the superior‐inferior level of diaphragm were contoured on the average CT. An SBRT plan, using Rapid Arc, was generated for the average CT. The prescribed dose to the PTV was 24Gy in 3 fractions using V24Gy=95%. The plan was next copied to each of the 10 CT sets for dose calculation. The dose‐volume parameters Dmax and D95% for PTV, and Dmax, D0.25cc, D1.2cc for thecal sac at each respiratory phase CT were compared with those obtained from the average CT. ' Results: The variations of dosimetric parameters for each phase of 4D‐CT relative to the average CT demonstrate similar respiratory shapes. For case #1, all phases, the thecal sac Dmax are higher than that of average CT, and the D0.25cc of thecal sac are lower compared to average CT. For case #4, the thecal sac Dmax for all phases are lower compared with average CT. In this case, the Dmax of thecal sac calculated on the helical CT might be underestimated by 7.3%. Conclusion: Planning on helical CT for spine SBRT at the level of diaphragm might introduce deviations to the thecal sac dose. In such cases, the average CT should be used for dose calculation.

Reirradiation with Stereotactic Body Radiotherapy: Analysis of Human Spinal Cord Tolerance Using the Generalized Linear–Quadratic Model

Using the generalized linear-quadratic (gLQ) model, we reanalyzed published dosimetric data from patients with radiation myelopathy (RM) after reirradiation with spinal stereotactic body radiotherapy (SBRT). Based on a published study, the thecal sac dose of five RM patients and 14 no RM patients were reanalyzed using gLQ model. Maximum point doses (Pmax) in the thecal sac were obtained. The gLQ-based biological effective doses were calculated and normalized (nBEDgLQ) to a 2-Gy equivalent dose (nBEDgLQ = Gy2/2_gLQ). The initial conventional radiotherapy dose, converted to Gy2/2_gLQ, was added. Total (conventional radiotherapy + SBRT) mean Pmax nBEDgLQ was lower in no RM than RM patients: 59.2 Gy2/2_gLQ (range: 37.5-101.9) versus 94.8 Gy2/2_gLQ (range: 70.2-133.4) (p = 0.0016). The proportion of total Pmax nBEDgLQ accounted for by the SBRT Pmax nBEDgLQ was higher for RM patients. No RMs were seen below a total spinal cord nBEDgLQ of 70 Gy2/2_gLQ. The gLQ-derived spinal cord tolerance for total nBEDgLQ was 70 Gy2/2_gLQ.

Stereotactic Body Radiotherapy for the Treatment of Spinal Metastases: An Overview of the University of Toronto, Sunnybrook Health Sciences Odette Cancer Centre, Technique

Conventional low-dose radiation therapy (RT) has long been used in the treatment of patients suffering from the symptoms of metastatic cancer in and around the spine. The goals of therapy include pain control and at least short-term local disease control. Most patients are offered palliative doses such as 8 Gy in one fraction, 20 Gy in five fractions, or 30 Gy in 10 fractions, and as yet there has been no dose–response relationship within conventional RT practice. Stereotactic body radiation therapy (SBRT) is a relatively new technique that overcomes the previous limitations of conventional RT by delivering high biologically effective doses (BED), in the range of what is considered locally curative, using intensity-modulated radiotherapy (IMRT). Doses such as 16–24 Gy in a single fraction, 24–30 Gy in two or three fractions, and 30–40 Gy in four or five fractions are commonly used in spine SBRT, while sparing the surrounding normal tissues to a much lower dose that falls within tolerance. The high precision required for spine SBRT demands near-rigid patient immobilization, visualization of the target volume and spinal cord with magnetic resonance imaging, and image-guided radiotherapy. Ultimately, an overall delivery precision of approximately 1.5-2 mm is required for safe and effective treatment. The aim of this review is to discuss the technical delivery of spine SBRT with particular attention to the incorporation of robotic treatment couch technology. The HexaPOD (Elekta AB, Stockholm, Sweden) is the robotic couch in use at the University of Toronto, and it is capable of performing fine translations and rotations allowing for six degrees of freedom patient positioning. This technology is a major advancement in correcting patient setup errors.

Stereotactic body radiotherapy: a new paradigm in the management of spinal metastases.

Spine stereotactic body radiotherapy is based on delivering high biologically effective doses to spinal metastases, with the intent to maximize both tumor and pain control. The purpose of this review is to outline the technical details of spine stereotactic body radiotherapy, contrast clinical outcomes to low biologically effective dose conventional palliative radiotherapy, discuss the role of surgery in the era of spine stereotactic body radiotherapy, and summarize the major serious adverse events that patients would otherwise not be at risk of with conventional radiotherapy.

Pain Flare Is a Common Adverse Event in Steroid-Naïve Patients After Spine Stereotactic Body Radiation Therapy: A Prospective Clinical Trial

To determine the incidence of pain flare after spine stereotactic body radiation therapy (SBRT) in steroid-naïve patients and identify predictive factors. Forty-one patients were treated with spine SBRT between February 2010 and April 2012. All patients had their pain assessed at baseline, during, and for 10 days after SBRT using the Brief Pain Inventory. All pain medications were recorded daily and narcotics converted to an oral morphine equivalent dose. Pain flare was defined as a 2-point increase in worst pain score as compared with baseline with no decrease in analgesic intake, a 25% increase in analgesic intake as compared with baseline with no decrease in worst pain score, or if corticosteroids were initiated at any point during or after SBRT because of pain. The median age and Karnofsky performance status were 57.5 years (range, 27-80 years) and 80 (range, 50-100), respectively. Eighteen patients were treated with 20-24 Gy in a single fraction, whereas 23 patients were treated with 24-35 Gy in 2-5 fractions. Pain flare was observed in 68.3% of patients (28 of 41), most commonly on day 1 after SBRT (29%, 8 of 28). Multivariate analysis identified a higher Karnofsky performance status (P=.02) and cervical (P=.049) or lumbar (P=.02) locations as significant predictors of pain flare. In those rescued with dexamethasone, a significant decrease in pain scores over time was subsequently observed (P<.0001). Pain flare is a common adverse event after spine SBRT and occurs most commonly the day after treatment completion. Patients should be appropriately consented for this adverse event.