ESTRO 2023 - Abstract Book

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ESTRO 2023

of local recurrence rate was 21.9% (SRT) vs 0% (CPBI) (P<0.037). The crude rate of radiation necrosis was 18.8% (SRT) vs 0% (CPBI) (p = 0.064, NS). The mean cavity volume was 10cc (SRT) vs 37cc (CPBI), (p <0.001). Distal rates of brain recurrence were 37.5% (SRT) vs 80% (CPBI) (p = 0.003), but this was no longer significant on multivariate analysis. Conclusion In this single institution cohort, stereotactic radiation therapy was statistically associated with a higher risk of both local failure and radiation necrosis as compared to conformal partial brain irradiation. Despite the cavity being much larger, none of the CPBI patients suffered either local failure or radiation necrosis. Post-operative CPBI may represent a safer and more effective treatment than the current standard of care and should be compared to RS in a prospective randomized trial. K. Zhelev 1 , M. Cholakova 1 , B. Atanasova 1 , R. Lazarov 1 , M. Mihaylova - Hristova 2 , I. Mihaylova 3 , N. Conev 4 , M. Petrova 5 , I. Donev 5 1 MHAT Heart and Brain, Radiotherapy, Pleven, Bulgaria; 2 National Oncology Hospital, Nuclear Medicine, Sofia, Bulgaria; 3 National Oncology Hospital, Radiotherapy, Sofia, Bulgaria; 4 UMHAT St. Marina, Medical Oncology, Varna, Bulgaria; 5 MHAT Nadezhda, Medical Oncology, Sofia, Bulgaria Purpose or Objective Sarcopenia (low muscle mass) is a syndrome associated with poor outcome in cancer patients. Temporal muscle thickness (TMT) is a novel biomarker of sarcopenia, however there is no detailed research to establish its significance in patients with glioblasoma multiforme (GBM). We investigated the prognostic and predictive performance of TMT measured on brain MRIs in patients with primary GBM, treated with concurrent chemoradiotherapy with temozolamide (TMZ). Materials and Methods Data of 57 patients with primary GBM grade IV who were not feasible for total resection were retrospectively analyzed between November 2016 and April 2021. All patients were treated with subtotal resection (STR) or open biopsy and after that with concurrent chemoradiotherapy with TMZ. TMT was measured bilaterally on axial thin slice (1mm cut) contrast enhanced T1-weighted MRI images perpendicular to the long axis of the temporal muscle at the level of the orbital roof prior treatment. The axial MRI plane was oriented parallel to the anterior commissure - posterior commissure line. The median value of TMT (15.2mm) was used to divide patients into patients with or without sarcopenia. Results The cohort included 35 men (61.4%) and 22 women (38.6%), with a total mean age of 54.1±8 years. Patients with performance status (PS) 1 were 38 (66.7%) and PS 2 - 19 (33.3%). Sarcopenia was present in 29 (50.8%) patients, of which 16 (55.2%) men and 13 (44.8%) woman. Presence of sarcopenia was related only to patients Eastern Cooperative Oncology Group (ECOG) performance status (PS) (p=0.003) and gross tumor volume (GTV) (p=0.002). A significantly negative correlation was detected between TMT and GTV (rho = - 0.263; p=0.048). Patients with PS 2 had significantly lower TMT and higher GTV than patients with PS 1. There was no significant difference in TMT between gender. Patients with sarcopenia had a significantly shorter mean progression - free survival (PFS) than patients without sarcopenia (6.01 months, 95% CI: 4.15-7.19 vs 13.57 months, 95% CI: 10.21-16.92; p<0.001). Patients with sarcopenia had a significantly shorter mean overall survival (OS) than patients without sarcopenia (10.01 months, 95% CI: 7.96–12.06 vs 28.39 months, 95% CI: 21.14–35.64; p<0.001). Moreover, when controlling for age, sex and PS presence of sarcopenia was independent poor prognostic marker in multiple Cox regression model (HR=7.11, 95% CI 2.62-19.27; p<0.001). Conclusion Low TMT is an independent predictor for poor outcome in patients with GBM treated with concurrent chemoradiotherapy. J. Li 1 , T. Beckham 1 , A. Ghia 1 , M.F. McAleer 1 , T. Swanson 1 , C. Wang 1 , D. Yeboa 1 , M. Tom 1 , S. Perni 1 , T. Briere 2 , Y. Yang 1 , E.B. Ludmir 3 , S. Zhang 1 , R. North 4 , C. Alvarez-Breckenridge 5 , L. Rhines 4 , B. Amini 6 , C. Tatsui 4 1 University of Texas - MD Anderson Cancer Center, Radiation Oncology, HOUSTON, USA; 2 University of Texas - MD Anderson Cancer Center, Radiation Physics, HOUSTON, USA; 3 University of Texas - MD Anderson Cancer Center, Radiation Oncology, Houston, USA; 4 University of Texas - MD Anderson Cancer Center, Neurosurgery, HOUSTON, USA; 5 Alvarez-Breckenridge, Neurosurgery, HOUSTON, USA; 6 University of Texas - MD Anderson Cancer Center, Diagnostic Radiology, HOUSTON, USA Purpose or Objective SSRS (spinal stereotactic radiosurgery) is highly effective in providing local control (LC) for spinal metastases; however, higher local failure has been reported in patients with epidural compression. In this study we present the results of a consecutive series of patients treated with percutaneous spinal laser interstitial thermal therapy (sLITT) to manage thoracic epidural spinal cord compression (ESCC) in combination with or as salvage to SSRS. Materials and Methods A retrospective review from 2013 to 2022 was performed. Data collected included demographic, pathology, clinical, complications, pre and post-ESCC score (0,1a,1b,1c,2,3), location (vertebral body/paraspinal), length of hospital stay, interval to start adjuvant SSRS and systemic treatments. Independent-sample t-tests were used to compare means between pre- and post-sLITT treatments. Survival was estimated by the Kaplan-Meier method. Multivariate logistic regression was used to analyze predictive factors for local recurrence. PO-1142 Low TMT may be a negative predictive and prognostic marker in patients with GBM treated with CCRT PO-1143 Combining spinal LITT and SSRS for treatment of thoracic spinal metastases with epidural compression