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Background: To evaluate the possible advantages of a simple spinal cord (SC) dose‐limiting three‐dimensional conformal radiotherapy (3D‐CRT) technique in comparison to conventional two‐dimensional (2D) techniques and other 3D‐CRT techniques for spinal bone irradiation. Methods: For 41 spinal target volumes, seven different techniques were evaluated, using a standard schedule of 30 Gy in 10 fractions. The SC dose‐limiting 3D‐CRT technique 1F2S‐18MV using a single posterior field (F) supplemented by two anterior segment fields (S) and 18‐MV photon beams was compared to two conventional 2D techniques (a single posterior field, PA, and two opposed anterior‐posterior fields, APPA), three other 3D‐CRT techniques (a single posterior field supplemented by four segment fields, 1F4S; two wedged fields, WD, and the SC dose‐limiting variant using 6 MV, 1F2S‐6MV) along with the original clinically applied plans. Results: 1F2S‐18MV demonstrated notably better results for all target volume parameters compared to the conventional 2D techniques (p < 0.001). Limitation of the SC dose was significantly superior with 1F2S‐18MV in comparison to PA and APPA (SC Dmean: 28.9 ± 0.4 vs. 30.1 ± 0.6 Gy and 30.1 ± 0.4 Gy; SC Dmax: 30.9 ± 0.7 vs. 32.5 ± 1.0 Gy and 31.8 ± 0.7 Gy; SC D1cm3: 30.1 ± 0.6 vs. 31.7 ± 0.9 Gy and 31.1 ± 0.6 Gy; p < 0.001). Likewise, lower mean SC doses with 1F2S‐18MV were observed in comparison to the more treatment time‐consuming 3D‐CRT techniques (1F4S, WD) and the original plans without relevant compromises on the dose homogeneity in the target volume and the dose exposure to the other OARs. Conclusion: In treatment planning of spinal metastases, simple variants of 3D‐CRT‐techniques like 1F2S‐18MV can offer a significant dose limitation to the SC while providing a sufficient dose coverage of the target volume. Especially in patients with favorable life expectancy and potential need for re‐irradiation, such SC dose‐limiting 3D‐CRT techniques may be a reasonable approach. [ABSTRACT FROM AUTHOR]

In locally advanced rectal cancer (LARC) neoadjuvant chemoradiotherapy is regarded as standard treatment. We assessed acute toxicities in patients receiving conventional 3D-conformal radiotherapy (3D-RT) and correlated them with dosimetric parameters after re-planning with volumetric modulated arc therapy (VMAT). Patients were randomized within the multicenter CAO/ARO/AIO-12 trial and received 50.4 Gy in 28 fractions and simultaneous chemotherapy with fluorouracil and oxaliplatin. Organs at risk (OAR) were contoured in a standardized approach. Acute toxicities and dose volume histogram parameters of 3D-RT plans were compared to retrospectively calculated VMAT plans. From 08/2015 to 01/2018, 35 patients with LARC were treated at one study center. Thirty-four patients were analyzed of whom 1 (3%) was UICC stage II and 33 (97%) patients were UICC stage III. Grade 3 acute toxicities occurred in 5 patients (15%). Patients with acute grade 1 cystitis (n = 9) had significantly higher Dmean values for bladder (29.4 Gy vs. 25.2 Gy, p < 0.01) compared to patients without bladder toxicities. Acute diarrhea was associated with small bowel volume (grade 2: 870.1 ccm vs. grade 0–1: 647.3 ccm; p < 0.01) and with the irradiated volumes V5 to V50. Using VMAT planning, we could reduce mean doses and irradiated volumes for all OAR: Dmean bladder (21.9 Gy vs. 26.3 Gy, p < 0.01), small bowel volumes V5–V45 (p < 0.01), Dmean anal sphincter (34.6 Gy vs. 35.6 Gy, p < 0.01) and Dmean femoral heads (right 11.4 Gy vs. 25.9 Gy, left 12.5 Gy vs. 26.6 Gy, p < 0.01). Acute small bowel and bladder toxicities were dose and volume dependent. Dose and volume sparing for all OAR could be achieved through VMAT planning and might result in less acute toxicities. [ABSTRACT FROM AUTHOR]

Background: Despite of a multimodal approach, recurrences can hardly be prevented in glioblastoma. This may be in part due to so called glioma stem cells. However, there is no established marker to identify these stem cells. Methods: Paired samples from glioma patients were analyzed by immunohistochemistry for expression of the following stem cell markers: CD133, Musashi, Nanog, Nestin, octamer-binding transcription factor 4 (Oct4), and sex determining region Y-box 2 (Sox2). In addition, the expression of osteopontin (OPN) was investigated. The relative number of positively stained cells was determined. By means of Kaplan–Meier analysis, a possible association with overall survival by marker expression was investigated. Results: Sixty tissue samples from 30 patients (17 male, 13 female) were available for analysis. For Nestin, Musashi and OPN a significant increase was seen. There was also an increase (not significant) for CD133 and Oct4. Patients with mutated Isocitrate Dehydrogenase-1/2 (IDH-1/2) status had a reduced expression for CD133 and Nestin in their recurrent tumors. Significant correlations were seen for CD133 and Nanog between OPN in the primary and recurrent tumor and between CD133 and Nestin in recurrent tumors. By confocal imaging we could demonstrate a co-expression of CD133 and Nestin within recurrent glioma cells. Patients with high CD133 expression had a worse prognosis (22.6 vs 41.1 months, p = 0.013). A similar trend was seen for elevated Nestin levels (24.9 vs 41.1 months, p = 0.08). Conclusions: Most of the evaluated markers showed an increased expression in their recurrent tumor. CD133 and Nestin were associated with survival and are candidate markers for further clinical investigation. [ABSTRACT FROM AUTHOR]

Purpose: To compare radiotherapy plans between an O‐ring and a conventional C‐arm linac for hypofractionated high‐dose prostate radiotherapy in terms of plan quality, dose distribution, and quality assurance in a multi‐vendor environment. Methods: Twenty prostate cancer treatment plans were irradiated on the O‐ring Varian Halcyon linac and were re‐optimized for the C‐arm Elekta Synergy Agility linac. Dose‐volume histogram metrics for target coverage and organ at risk dose, quality assurance, and monitor units were retrospectively compared. Patient‐specific quality assurance with ion chamber measurements, gamma index analysis, and portal dosimetry was performed using the Varian Portal Dosimetry system and the ArcCHECK® phantom (Sun Nuclear Corporation). Prostate‐only radiotherapy was delivered with simultaneous integrated boost (SIB) volumetric modulated arc therapy (VMAT) in 20 fractions of 2.5/3.0 Gy each. Results: For both linacs, target coverage was excellent and plan quality comparable. Homogeneity in PTVBoost was high for Synergy as well as Halcyon with a mean homogeneity index of 0.07 ± 0.01 and 0.05 ± 0.01, respectively. Mean dose for the organs at risk rectum and bladder differed not significantly between the linacs but were higher for the femoral heads and penile bulb for Halcyon. Quality assurance showed no significant differences in terms of ArcCHECK gamma pass rates. Median pass rate for 3%/2 mm was 99.3% (96.7 to 99.8%) for Synergy and 99.8% (95.6 to 100%) for Halcyon. Agreement between calculated and measured dose was high with a median deviation of −0.6% (−1.7 to 0.8%) for Synergy and 0.2% (−0.6 to 2.3%) for Halcyon. Monitor units were higher for the Halcyon by approximately 20% (p < 0.001). Conclusion: Hypofractionated high‐dose prostate cancer SIB VMAT on the Halcyon system is feasible with comparable plan quality in reference to a standard C‐arm Elekta Synergy linac. [ABSTRACT FROM AUTHOR]

Purpose: Integrating moderate hypofractionation to the macroscopic tumor with elective nodal irradiation while sparing the organs at risk (OAR) in chemoradiotherapy of locally advanced non-small-cell lung cancer.Methods: From 2010-2018, treatment, patient and tumor characteristics of 138 patients from two radiation therapy centers were assessed. Chemoradiotherapy by intensity-modulated radiation therapy (IMRT) with a simultaneous integrated boost (SIB) to the primary tumor and macroscopic lymph node metastases was used.Results: A total of 124 (90%) patients received concurrent chemotherapy. 106 (76%) patients had UICC (Union for International Cancer Control) stage ≥IIIB and 21 (15%) patients had an oligometastatic disease (UICC stage IV). Median SIB and elective total dose was 61.6 and 50.4 Gy in 28 fractions, respectively. Furthermore, 64 patients (46%) had an additional sequential boost to the primary tumor after the SIB-IMRT main series: median 6.6 Gy in median 3 fractions. The median cumulative mean lung dose was 15.6 Gy (range 6.2-29.5 Gy). Median follow-up and radiological follow-up for all patients was 18.0 months (range 0.6-86.9) and 16.0 months (range 0.2-86.9), respectively. Actuarial local control rates at 1, 2 and 3 years were 80.4, 68.4 and 57.8%. Median overall survival and progression-free survival was 30.0 months (95% confidence interval [CI] 23.5-36.4) and 12.1 months (95% CI 8.2-16.0), respectively. Treatment-related toxicity was moderate. Radiation-induced pneumonitis grade 2 and grade 3 occurred in 13 (9.8%) and 3 (2.3%) patients.Conclusions: Chemoradiotherapy using SIB-IMRT showed promising local tumor control rates and acceptable toxicity in patients with locally advanced and in part oligometastatic lung cancer. The SIB concept, resulting in a relatively low mean lung dose, was associated with low numbers of clinically relevant pneumonitis. The overall survival appears promising in the presence of a majority of patients with UICC stage ≥IIIB disease. [ABSTRACT FROM AUTHOR]

Data of thoracic in-field reirradiation with two courses of stereotactic body radiotherapy (SBRT) is scarce. Aim of this study is to investigate feasibility and safety of this approach. Patients with a second course of thoracic SBRT and planning target volume (PTV) overlap were analyzed in this retrospective, multicenter study. All plans and clinical data were centrally collected. 27 patients from 8 centers have been amenable for evaluation: 12 with non-small-cell lung cancer, 16 with metastases, treated from 2009 (oldest first course) to 2020 (latest second course). A median dose of 38.5 Gy to the 65%-isodose over a median of 5 fractions was prescribed in the first course and 40 Gy in 5 fractions for the second SBRT-course. Median PTV of the second SBRT was 29.5 cm3, median PTV overlap 22 cm3. With a median interval of 20.2 months between the two SBRT-courses, 1-year OS, and -LCR were 78.3% and 70.3% respectively. 3 patients developed grade 1 and one grade 2 pneumonitis. No grade > 2 toxicity was observed. Peripheral location and dose were the only factors correlating with tumor control. A second SBRT-course with PTV overlap appears safe and achieves reasonable local control. [ABSTRACT FROM AUTHOR]

Background: The objective of this study was to prospectively evaluate dose-intensified hypofractionated stereotactic body radiation therapy (SBRT) in patients with painful spinal metastases in a multicenter, single-arm, phase 2 study.Methods: Patients with 2 or fewer distinct, noncontiguous, painful, mechanically stable, unirradiated spinal metastases from a solid tumor with a Karnofsky performance status ≥ 60 were eligible. Patients with a long (Mizumoto score ≤ 4) or intermediate overall survival expectancy (Mizumoto score = 5-9) received 48.5 Gy in 10 fractions or 35 Gy in 5 fractions, respectively, with SBRT. The primary outcome was the overall (complete and partial) pain response as measured with international consensus guidelines 3 months after SBRT.Results: There were 57 patients enrolled between 2012 and 2015, and 54 of these patients with 60 painful vertebral metastases were analyzed. The 3-month pain response was evaluated in 42 patients (47 lesions). An overall pain response was observed in 41 lesions (87%), and the pain response remained stable for at least 12 months. The mean maximum pain scores on a visual analogue scale significantly improved from the baseline of 6.1 (standard deviation, 2.5) to 2.0 (standard deviation, 2.3) 3 months after treatment (P < .001). The 5-level EuroQol 5-Dimension Questionnaire quality-of-life (QOL) dimensions (self-reported mobility, usual activities, and pain/discomfort) significantly improved from the baseline to 3 months after treatment. The 12-month overall survival and local control rates were 61.4% (95% confidence interval [CI], 48%-74.8%) and 85.9% (95% CI, 76.7%-95%), respectively. Grade 3 toxicity was limited to acute pain in 1 patient (2%). No patient experienced radiation-induced myelopathy. Six patients (11%) developed progressive vertebral compression fractures (VCFs), and 8 patients (15%) developed new VCFs.Conclusions: Dose-intensified SBRT achieved durable local metastasis control and resulted in pronounced and long-term pain responses and improved QOL. Cancer 2018;124:2001-9. © 2018 American Cancer Society. [ABSTRACT FROM AUTHOR]

Object: Stereotactic body radiotherapy (SBRT) for vertebral metastases has emerged as a promising technique, offering high rates of symptom relief and local control combined with low risk of toxicity. Nonetheless, local failure or vertebral instability may occur after spine SBRT, generating the need for subsequent surgery in the irradiated region. This study evaluated whether there is an increased incidence of surgical complications in patients previously treated with SBRT at the index level.Methods: Based upon a retrospective international database of 704 cases treated with SBRT for vertebral metastases, 30 patients treated at 6 different institutions were identified who underwent surgery in a region previously treated with SBRT.Results: Thirty patients, median age 59 years (range 27-84 years) underwent SBRT for 32 vertebral metastases followed by surgery at the same vertebra. Median follow-up time from SBRT was 17 months. In 17 cases, conventional radiotherapy had been delivered prior to SBRT at a median dose of 30 Gy in median 10 fractions. SBRT was administered with a median prescription dose of 19.3 Gy (range 15-65 Gy) delivered in median 1 fraction (range 1-17) (median EQD2/10 = 44 Gy). The median time interval between SBRT and surgical salvage therapy was 6 months (range 1-39 months). Reasons for subsequent surgery were pain (n = 28), neurological deterioration (n = 15) or fracture of the vertebral body (n = 13). Open surgical decompression (n = 24) and/or stabilization (n = 18) were most frequently performed; Five patients (6 vertebrae) were treated without complications with vertebroplasty only. Increased fibrosis complicating the surgical procedure was explicitly stated in one surgical report. Two durotomies occurred which were closed during the operation, associated with a neurological deficit in one patient. Median blood loss was 500 ml, but five patients had a blood loss of more than 1 l during the procedure. Delayed wound healing was reported in two cases. One patient died within 30 days of the operation.Conclusion: In this series of surgical interventions following spine SBRT, the overall complication rate was 19%, which appears comparable to primary surgery without previous SBRT. Prior spine SBRT does not appear to significantly increase the risk of intra- and post-surgical complications. [ABSTRACT FROM AUTHOR]

Background: Evaluation of set up error detection by a transperineal ultrasound in comparison with a cone beam CT (CBCT) based system in external beam radiation therapy (EBRT) of prostate cancer. Methods: Setup verification was performed with transperineal ultrasound (TPUS) and CBCT for 10 patients treated with EBRT for prostate cancer. In total, 150 ultrasound and CBCT scans were acquired in rapid succession and analyzed for setup errors. The deviation between setup errors of the two modalities was evaluated separately for each dimension. Results: A moderate correlation in lateral, vertical and longitudinal direction was observed comparing the setup errors. Mean differences between TPUS and CBCT were (-2.7 ± 2.3) mm, (3.0 ± 2.4) mm and (3.2 ± 2.7) mm in lateral, vertical and longitudinal direction, respectively. The mean Euclidean difference between TPUS and CBCT was (6.0 ± 3.1) mm. Differences up to 19.2 mm were observed between the two imaging modalities. Discrepancies between TPUS and CBCT of at least 5 mm occurred in 58 % of monitored treatment sessions. Conclusion: Setup differences between TPUS and CBCT are 6 mm on average. Although the correlation of the setup errors determined by the two different image modalities is rather week, the combination of setup verification by CBCT and intrafraction motion monitoring by TPUS imaging can use the benefits of both imaging modalities. [ABSTRACT FROM AUTHOR]

Background: The 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.Methods: Four 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.Results: Averaged 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.Conclusions: Results 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. [ABSTRACT FROM AUTHOR]

Copyright of Strahlentherapie und Onkologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose To evaluate patient selection criteria, methodology, safety and clinical outcomes of stereotactic body radiotherapy (SBRT) for treatment of vertebral metastases. Materials and methods Eight centers from the United States (n = 5), Canada (n = 2) and Germany (n = 1) participated in the retrospective study and analyzed 301 patients with 387 vertebral metastases. No patient had been exposed to prior radiation at the treatment site. All patients were treated with linacbased SBRT using cone-beam CT image-guidance and online correction of set-up errors in six degrees of freedom. Results 387 spinal metastases were treated and the median follow-up was 11.8 months. The median number of consecutive vertebrae treated in a single volume was one (range, 1-6), and the median total dose was 24Gy (range 8-60Gy) in 3 fractions (range 1-20). The median EQD210 was 38Gy (range 12-81Gy). Median overall survival (OS) was 19.5 months and local tumor control (LC) at two years was 83.9%. On multivariate analysis for OS, male sex (p < 0.001; HR = 0.44), performance status <90 (p < 0.001; HR = 0.46), presence of visceral metastases (p = 0.007; HR = 0.50), uncontrolled systemic disease (p = 0.007; HR = 0.45), >1 vertebra treated with SBRT (p = 0.04; HR = 0.62) were correlated with worse outcomes. For LC, an interval between primary diagnosis of cancer and SBRT of ⩽30 months (p = 0.01; HR = 0.27) and histology of primary disease (NSCLC, renal cell cancer, melanoma, other) (p = 0.01; HR = 0.21) were correlated with worse LC. Vertebral compression fractures progressed and developed de novo in 4.1% and 3.6%, respectively. Other adverse events were rare and no radiation induced myelopathy reported. Conclusions This multi-institutional cohort study reports high rates of efficacy with spine SBRT. At this time the optimal fractionation within high dose practice is unknown. [ABSTRACT FROM AUTHOR]

Purpose: Patients with long life expectancy despite metastatic status might benefit from long-term local control of spinal metastases. Dose-intensified radiotherapy (RT) is believed to control tumor growth better and thus offers longer pain relief. This single-institution study reports on fractionated stereotactic body radiation therapy (SBRT) for spinal metastases in patients with good life expectancy based on performance status, extent of metastases, histology, and time to metastasis.Methods: Between 2004 and 2010, 36 treatment sites in 32 patients (median age 55 years; male 61%; median Karnofsky performance score 85) were treated with fractionated SBRT. The median treatment dose was 60 Gy (range, 48.5-65 Gy) given in a median of 20 fractions (range, 17-33); the median maximum dose to the planning risk volume for the spinal cord (PRV-SC) was 46.6 Gy.Results: All patients suffering from pain prior to RT reported pain relief after treatment; after a median follow-up of 20.3 months, 61% of treatment sites were pain-free, another 25% associated with mild pain. In 86% of treatments, patients were free from neurological symptoms at the time of the last clinical follow-up. Acute grade 1 toxicities (CTCAE 3.0) were observed in 11 patients. Myelopathy did not occur in any patient. Radiologically controlled freedom from local progression was 92 and 84% after 12 and 24 months, respectively. Median overall survival (OS) was 19.6 months.Conclusion: Patient selection resulted in long OS despite metastatic disease, and dose-intensified fractionated SBRT for spinal metastases was safe and achieved long-term local tumor control and palliation of pain. [ABSTRACT FROM AUTHOR]

Although locoregional relapse is frequent after definitive radiotherapy (RT) or multimodal treatments, re-irradiation is only performed in few patients even in palliative settings like e.g. vertebral metastasis. This is most due to concern about potentially severe complications, especially when large volumes are exposed to re-irradiation. With technological advancements in treatment planning the interest in re-irradiation as a local treatment approach has been reinforced. Recently, several studies reported re-irradiation for spinal metastases using SBRT with promising local and symptom control rates and simultaneously low rates of toxicity. These early data consistently indicate that SBRT is a safe and effective treatment modality in this clinical situation, where other treatment alternatives are rare. Similarly, good results have been shown for SBRT in the re-irradiation of head and neck tumors. Despite severe late adverse effects were reported in several studies, especially after single fraction doses >10 Gy, they appear less frequently compared to conventional radiotherapy. Few studies with small patient numbers have been published on SBRT re-irradiation for non-small cell lung cancer (NSCLC). Overall survival (OS) is limited by systemic progression and seems to depend particularly on patient selection. SBRT re-irradiation after primary SBRT should not be practiced in centrally located tumors due to high risk of severe toxicity. Only limited data is available for SBRT re-irradiation of pelvic tumors: feasibility and acceptable toxicity has been described, suggesting SBRT as a complementary treatment modality for local symptom control [ABSTRACT FROM AUTHOR]

Copyright of Strahlentherapie und Onkologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Autoimmune diseases and cancer can be treated by influencing the immune system. Apo and nec cells are strong modulators of the immune system contributing to anti-inflammatory and pro-inflammatory responses, respectively. We examined which form of cell death was induced by HT and X-irradiation. Nec was the prominent form of cell death after combined treatment and the amount of dead cells was higher when exposing the cells to radiation before HT. Combined applications further led to an increased percentage of cells in a more radioresponsive G2 cell cycle phase. The danger signal HMGB1 is released when combining HT with radiation, a further hint that those treatments may induce inflammation and immune activation. We conclude that immune responses are appropriately adapted to the damage that has occurred and may contribute to anti-cancer immunity or chronic autoimmunity, respectively. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate patient selection criteria, methodology, safety and clinical outcomes of stereotactic body radiotherapy (SBRT) for treatment of vertebral metastases.Materials and Methods: Eight centers from the United States (n=5), Canada (n=2) and Germany (n=1) participated in the retrospective study and analyzed 301 patients with 387 vertebral metastases. No patient had been exposed to prior radiation at the treatment site. All patients were treated with linac-based SBRT using cone-beam CT image-guidance and online correction of set-up errors in six degrees of freedom.Results: 387 spinal metastases were treated and the median follow-up was 11.8 months. The median number of consecutive vertebrae treated in a single volume was one (range, 1-6), and the median total dose was 24 Gy (range 8-60 Gy) in 3 fractions (range 1-20). The median EQD210 was 38 Gy (range 12-81 Gy). Median overall survival (OS) was 19.5 months and local tumor control (LC) at two years was 83.9%. On multivariate analysis for OS, male sex (p<0.001; HR=0.44), performance status <90 (p<0.001; HR=0.46), presence of visceral metastases (p=0.007; HR=0.50), uncontrolled systemic disease (p=0.007; HR=0.45), >1 vertebra treated with SBRT (p=0.04; HR=0.62) were correlated with worse outcomes. For LC, an interval between primary diagnosis of cancer and SBRT of ≤ 30 months (p=0.01; HR=0.27) and histology of primary disease (NSCLC, renal cell cancer, melanoma, other) (p=0.01; HR=0.21) were correlated with worse LC. Vertebral compression fractures progressed and developed de novo in 4.1% and 3.6%, respectively. Other adverse events were rare and no radiation induced myelopathy reported.Conclusions: This multi-institutional cohort study reports high rates of efficacy with spine SBRT. At this time the optimal fractionation within high dose practice is unknown. [ABSTRACT FROM AUTHOR]

Although locoregional relapse is frequent after definitive radiotherapy (RT) or multimodal treatments, re-irradiation is only performed in few patients even in palliative settings like e.g. vertebral metastasis. This is most due to concern about potentially severe complications, especially when large volumes are exposed to re-irradiation. With technological advancements in treatment planning the interest in re-irradiation as a local treatment approach has been reinforced. Recently, several studies reported re-irradiation for spinal metastases using SBRT with promising local and symptom control rates and simultaneously low rates of toxicity. These early data consistently indicate that SBRT is a safe and effective treatment modality in this clinical situation, where other treatment alternatives are rare. Similarly, good results have been shown for SBRT in the re-irradiation of head and neck tumors. Despite severe late adverse effects were reported in several studies, especially after single fraction doses >10 Gy, they appear less frequently compared to conventional radiotherapy. Few studies with small patient numbers have been published on SBRT re-irradiation for non-small cell lung cancer (NSCLC). Overall survival (OS) is limited by systemic progression and seems to depend particularly on patient selection. SBRT re-irradiation after primary SBRT should not be practiced in centrally located tumors due to high risk of severe toxicity. Only limited data is available for SBRT re-irradiation of pelvic tumors: feasibility and acceptable toxicity has been described, suggesting SBRT as a complementary treatment modality for local symptom control. [ABSTRACT FROM AUTHOR]