ESTRO 2020 Abstract Book

S41 ESTRO 2020

Purpose or Objective To determine the maximum tolerated dose (MTD) of Volumetric Modulated Arc Therapy (VMAT) with standard concurrent and sequential dose temozolomide (TMZ) in patients with resected glioblastoma multiforme. Material and Methods A Phase I clinical trial was performed. Patients with histological proven glioblastoma underwent VMAT dose escalation. VMAT was delivered over 5 weeks with the simultaneous integrated boost (SIB) technique to the two planning target volumes (PTVs) defined by adding 5-mm margin to the respective clinical target volumes (CTVs). CTV1 was the tumor bed + MR enhancing residual lesion with a 10-mm margin; CTV2 was CTV1 plus 20-mm isotropic margin. VMAT was delivered in 25 fractions. Only the dose for PTV1 was escalated while maintaining the same dose for PTV2 (45 Gy/1.8 Gy). Four PTV1 dose levels were planned: Level 1 (77.5/3.1 Gy), Level 2 (80/3.2 Gy), Level 3 (82.5/3.3 Gy) and Level 4 (85/3.4 Gy). Patients were treated in cohorts of between three and six per group using a Phase I study design. The recommended dose was exceeded if one of the three patients in a cohort experienced dose-limiting toxicity within 3 months from treatment. Concurrent and sequential TMZ chemotherapy was administered according to Stupp’s protocol. Two arc techniques were used to cover at least 95% of the target volume with the 95% isodose line. Dose-limiting toxicity (DLT) were defined as any treatment-related non- haematological adverse effects rated as Grade > 3 or any haematological toxicity rated as > 4 by Radiation Therapy Oncology Group (RTOG) criteria. Results Twenty-one consecutive glioblastoma patients (male/female: 14/7; median age: 66 years) were treated. Dose to the PTV1: 10 patients 77.5 Gy; 9 patients, 80 Gy; 2 patients, 82.5 Gy,; 0 patients, 85 Gy. Median follow-up time was 10 months (range: 1-23.3 months). Grade 1-2 treatment-related neurological and cutaneous toxicities were registered (6 and 16 patients, respectively). Two patients experienced DLT to dose of 82.5 Gy (1 neurological toxicity grade 3, 1 haematological grade 4). Conclusion DMT was reached at the dose level of 82.5 Gy. Volumetric Modulated Arc Therapy in patients with resected glioblastoma multiforme to a dose of 80 Gy in 25 fractions is well tolerated with TMZ at a daily dose of 75 mg/mq. OC-0092 Neurocognitive function related to radiation dose after treatment for brain tumours in adults L. Haldbo-Classen 1 , A. Amidi 2 , L. Wu 3 , S. Lukacova 1 , G.V. Oettingen 4 , Y. Lassen 5 , R. Zachariae 2 , J.F. Kallehauge 5 , M. Høyer 5 1 Aarhus University Hospital, Oncology, Aarhus N, Denmark ; 2 Aarhus University Hospital and Aarhus University, Oncology- Unit for Psychooncology and Health Psychology- and Psychology and Behavioural Sciences, Aarhus N, Denmark ; 3 Aarhus University, Unit for Psychooncology and Health Psychology and Dept of Psychology and Behavioural Science and Advanced Studies, Aarhus C, Denmark ; 4 Aarhus University Hospital, Department of Neurosurgery, Aarhus N, Denmark ; 5 Aarhus University Hospital, Danish Center for Particle Therapy, Aarhus N, Denmark Purpose or Objective Radiation therapy (RT) is a fundamental part of treatment for brain tumours. Unfortunately, RT may be associated with neurocognitive impairment, and, in recent years, RT to the hippocampus has been investigated due to its important function in learning and memory. However, the relationship between RT dose and effects on neurocognitive function, have not been clearly established. The primary aim of this study was to examine if patients who had received high RT doses to the hippocampus would show impairment on the Hopkins

Patient cohorts were well-balanced in key socioeconomic (race, sex, insurance, income & education) & clinical characteristics (tumor site, grade, size & surgical margin status). Patients in the CRT arm were more likely to be younger (≤50) (44.9% vs 20.8%), have a Charlson-Deyo [CD] score of 0 (85.7% vs 79.3%) & have synovial sarcoma histology (19.6% vs 2.8%). The unadjusted 5-year KM OS was significantly higher in the CRT vs RT cohort: 72.0% vs 56.1% on univariate (p<0.0001) & multivariate analysis (Hazard Ratio [HR]: 0.57; 95% Confidence Interval [CI]: 0.41-0.78; p<0.001) even after adjusting for age, race, income, CD score, histology, tumor size, tumor grade & primary site (lower extremity; upper extremity; trunk). PSM identified evenly matched cohorts of 212 patients each with respect to age, income, CD score, histology, grade, tumor size & primary site. The adjusted 5-year KM OS was significantly higher in the CRT vs RT cohort: 69.8% vs 55.4%. The addition of neoadjuvant C remained prognostic for OS on PSM analysis (HR: 0.56 [0.39-0.83], p=0.003). There were no statistical differences in the mean surgical inpatient stay (3.8 vs 4.3 days), 30-day unplanned readmission rate (5.0% each), or 90-day mortality (2.0% vs 1.2%) between the RT vs CRT cohorts. Conclusion The addition of chemotherapy to neoadjuvant RT was associated with improved OS in patients with high risk ET- STS in the NCDB. Additionally, toxicity surrogates were similar between RT vs CRT cohorts. These findings warrant further investigation in a prospective randomized trial. OC-0089 Oncological & Functional outcomes of Extracorporeal Radiation and Reimplantation for Bone Sarcomas

Abstract withdrawn

SP-0090 Methodological challenges of clinical research in soft tissue sarcomas Paolo Casali Instituto Nazionale Tumori, Milan, Italy

Abstract not available

Proffered Papers: Proffered papers 4: CNS

OC-0091 SIB accelerated RT and concomitant TMZ in GBM patients: results of a phase I study (ISIDE BT-2) M. Ferro 1 , A. Ianiro 2 , A. Re 1 , G. Macchia 1 , S. Cilla 2 , V. Picardi 1 , M. Boccardi 1 , M. Ferro 1 , S. Cammelli 3 , C. Romano 2 , S. Bisello 3 , M. Buwenge 3 , S. Mignogna 4 , G. Giglio 5 , E. Cucci 6 , V. Valentini 7 , A.G. Morganti 3 , F. Deodato 1 1 Università Cattolica del Sacro Cuore, Radiation Oncology Department- Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy ; 2 Università Cattolica del Sacro Cuore, Medical Physics Unit- Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy ; 3 University of Bologna- S. Orsola-Malpighi Hospital, Radiation Oncology Center- Dept. of Experimental- Diagnostic and Specialty Medicine – DIMES, Bologna, Italy ; 4 Università Cattolica del Sacro Cuore, Oncology Department- Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy ; 5 ‘A. Cardarelli’ Hospital, Oncology Department, Campobasso, Italy ; 6 Università Cattolica del Sacro Cuore, Radiology Department- Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy ; 7 Università Cattolica del Sacro Cuore- Policlinico Universitario “A. Gemelli”, Radiotherapy- Radiology and Hematology Department – Gemelli ART Advanced Radiation Therapy, Roma, Italy