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Purpose: To determine the preferred conventional radiation therapy (CRT) practice, and willingness to randomize to high dose spine SBRT, in a group of patients with complex spinal metastases. Methods and Material: The survey was based on four complex spinal metastases cases, considered candidates for the proposed Phase 2 randomized controlled trial (RCT) comparing 24 Gy in 2 fractions delivered with SBRT to either 20 Gy in 5 fraction (frx) or 30 Gy in 10 frx CRT. Participants were asked to determine their preferred CRT practice, whether they would treat the same patient with SBRT, and if they would participate in the RCT. Two cases were of radioresistant histologies (renal cell and hepatocellular carcinoma), one had epidural disease, two were oligometastatic, and one consisted of a C2 level metastases with paraspinal extension. Results: 51 radiation oncologists from across the country participated. For each of the clinical scenarios, 20 Gy in 5 frx was the favored CRT practice. However, equivalence was noted for the one renal cell case. All respondents were comfortable with delivering the intended SBRT dose, and most would participate on the proposed RCT . With respect to the primary treatment intent, both local control (LC) and symptom relief were of primary importance; however, local control was more important than symptom relief for the two patients with oligometastatic disease and an expected long-term survival. 51 % of respondents would be able to randomize one patient per month and 35% could randomize 2 to 5 patients per month. Conclusion: 20Gy/5fx was the preferred CRT practice for the treatment of complex spinal metastases described in the survey. Most radiation oncologists surveyed would be willing to participate in the proposed Phase 2 RCT. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]

Purpose: Radiotherapy is a well-established treatment option for bone metastases. One of the commonly associated toxicities is pain flare, which can be broadly defined as a transient increase in pain during or immediately post-treatment. Previously published data indicates that incidence rates can be as high as 40% with conventional radiotherapy. With the emergence of stereotactic body radiotherapy (SBRT) as a high-dose alternative for spinal metastases, there is a need to define the pain flare phenomenon within this setting. The purpose of this prospective toxicity study was to determine the incidence rate of pain flare for SBRT of spinal metastases. Methods: From February 2010 to April 2012,41 patients were enrolled in this study. Pain scores were evaluated using the Brief Pain Inventory (BPI) before, during and 10 days after radiotherapy. Both analgesic and corticosteroid use was also documented. Pain flare was defined as per published criteria (i.e. two-point increase in worst pain on an 11-point numeric scale compared to baseline with no decrease in analgesic use, or 25% increase in analgesic intake with no decrease in worst pain score). The definition was slightly modified such that pain flare was also recorded if corticosteroids were initiated. Predictive factors were evaluated using univariate and multivariate logistic regression analysis. Results: Within this cohort, the mean (SD) age was 57.5 (12.4) years old with a median (range) KPS score of 80 (50-100). The most common primary sites were renal (36.6%), lung (24.4%) and breast (17.1%). The incidence of pain flare was 68.3% (28/41). The most common day of occurrence was day 1 post-radiotherapy (28.6%; 8/28). On multivariate logistic regression analysis, higher KPS (p=0.0174) and cervical (p=0.0498) or lumbar (p=0.0176) spine involvement were the factors significantly associated with pain flare. No association was noted for baseline pain scores, dose-fractionation schedule used or subsequent dosimetric data. Conclusions: With SBRT for spinal metastases, the incidence of pain flare was much higher than what would be expected for conventional radiotherapy. Our practice now is to offer prophylactic dexamethasone to all patients undergoing spine treatment. If validated with a larger cohort though, it may be possible to identify a high-risk subgroup that would allow for further individualization of care. At this time, this study represents the first attempt at characterizing pain flare secondary to spinal SBRT, the importance of which will only be underscored as its utility increases. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]

Objectives: To report the rate of post-stereotactic body radiotherapy (SBRT) vertebral compression fracture (VCF) specific to renal cell cancer (RCC) spinal metastases, and to identify potential anatomic and dosimetric predictive factors. Methods: 71 spinal segments in 37 RCC patients treated at the University of Toronto were retrospectively reviewed. All 71 spinal segments were scored at baseline according to the Spinal Instability Neoplastic Score (SINS) criteria to determine if the components of this scoring system are predictive for SBRT-induced VCF. Additional factors analysed included the use of anti-angiogenic therapies, biphosphonates, prior radiation, total dose and number of fractions, and various dose-volume histogram parameters. Post-operative tumours were considered separately. Results: According to the SINS criteria, 42/71 segments were stable, 24/71 potentially unstable, and 5/71 unstable at baseline. Of the 5 unstable segments, 2 underwent initial surgery prior to SBRT and 3 were considered inoperable and treated with SBRT alone. In total, post-operative SBRT was delivered for 10/71 spinal segments and the analysis confined to the 61 segments treated with SBRT alone. At baseline, 48/61 vertebral bodies had no fracture and 13 had some degree of fracture (4 had <10% and 9 had 10-33% of collapse). The median SBRT total dose and number of fractions were 24 Gy (range, 18-30) and 2 (range, 1-5), respectively. The median follow up was 12 months. 10 VCFs (16%) were observed with 3/10 being de novo fractures and 7/10 cases fracture progression. The 1-year fracture-free probability was 82%. The median time to VCF was 48 days. The risk of SBRT-induced VCF was significantly greater in patients with baseline VCF (7/13, 54%) compared to those with no baseline VCF (3/48, 6%). Multivariate analysis identified baseline VCF as the only significant predictor of SBRT-induced VCF (hazard ratio, 6.46; 95% CI, 1.04-40.17; p=0.05). Conclusion: We observe a manageable risk of SBRT-induced VCF in RCC patients. However, for spinal metastases with a baseline VCF, careful monitoring is required as they are at significantly greater risk of further collapse. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]

Objectives: Spine SBRT is increasingly being applied to the post-operative patient, as an alternative to conventional palliative radiotherapy, with the aim to improve upon existing rates of local control. As an emerging indication, our aim was to identify clinical and dosimetric predictors of local control and survival. Methods: 80 patients treated between October 2008 to February 2012 with post-operative SBRT within 8 weeks of surgery, were identified from our prospective database and retrospectively reviewed. The pre- and post-operative MR images were reviewed to characterize the disease extent within the spinal segment, and to grade epidural disease such that grade 0 is no epidural disease, grade 1 is dural compression without spinal cord displacement, grade 2 is cord compression with visible CSF and grade 3 is cord compression obliterating CSF. Other factors analyzed included type of surgery, use of systemic therapy post-SBRT, prior radiation exposure, total dose, dose per fraction and various dosimetric factors. Results: The median follow-up was 8.3 months (range, 0.2- 39.1). The most common primary histologies were breast (15%) and non-small cell lung cancer (15%), and 56% of tumors were in the thoracic spine. 69 (86%) patients underwent a decompressive surgery while 11 (14%) underwent a stabilization procedure alone. 35 (44%) patients were treated with 1 or 2 fractions (total dose ranging from 18-26), and 45 (56%) with 3 to 5 fractions (total dose ranging from 24-40). Pre- and postoperative epidural grade 0,1,2, and 3 were observed in 5%/7%, 35%/66%, 35%/10%, and 25%/0% of patients, respectively. 21 local failures (26%) were observed, and the 1-year local control (LC) and overall survival (OS) rates were 84% and 63%, respectively. The median time to local failure was 6.9 months (range, 0.2 - 37.4 months). The most common site of failure was within the epidural space (15/21,71%). We identified systemic therapy post-SBRT as the only significant predictor of OS (p=0.03). Multivariate proportional hazards analysis identified treatment with 1 or 2 fraction SBRT and a postoperative epidural disease grade of 0/1 as significant predictors of LC. Subset analysis for only those patients with a pre-operative epidural disease grade of 2 or 3 (n=48/80) indicated significantly greater LC rates when down-graded to 0/1 vs 2 (p=0.0009). Conclusions: At one year, 80% of patients remained progression free. 1 or 2 fraction SBRT and a postoperative epidural disease grade of 0 or 1 predicted for superior local control. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate local control (LC) and overall survival (OS) after stereotactic body radiation therapy (SBRT) for renal cell cancer (RCC) spinal metastases, and to evaluate predictive and prognostic factors, respectively. Methods: 71 spinal segments in 37 RCC patients treated at the University of Toronto were retrospectively reviewed. LC was assessed based on each spinal segment treated and OS according to each patient treated, using the Kaplan-Meier method. Oligometastatic disease (less than 5 sites of metastatic disease), paraspinal extension, invasion of posterior elements, grade of epidural disease, targeted anti-angiogenic therapy, prior radiation, total dose and number of fractions, and various dose-volume histogram metrics were evaluated for their prognostic and predictive significance. Results: Of the 71 spinal segments treated with SBRT, 9 were cervical, 33 thoracic, 21 lumbar, and 8 sacral. 11/71 had been previously radiated, and 10/71 were treated with post-operative SBRT. The median SBRT total dose and number of fractions were 24 Gy (range, 18-30) and 2 (range, 1-5), respectively. The median follow up was 12 months. The 1-year OS and LC rates were 64% and 83%, respectively. Patterns of failure included progression within the epidural space (5/12), paraspinal tissue (2/12), vertebral segment bone (2/12) and mixed (including epidural space; 3/12). Multivariate analysis indicated oligometastatic disease (13/37 patients) as the only significant prognostic factor for OS (p=0.018). We did not found any predictor for LC; total dose and number of fractions were not predictive. Conclusion: We identified the oligometastatic state as prognostic for RCC, therefore, a group deserving aggressive local therapy. Spine SBRT yielded high rates of local tumour control in this population. Disclosure: No significant relationships. [ABSTRACT FROM AUTHOR]