ESTRO 2020 Abstract book

S419 ESTRO 2020

II (90.1%), were partially resected in 64.5% and a median of 1 (0-6) cranial surgeries were performed before PT. The median prescribed dose was 59.4 Gy (RBE) (range, 40-75) to a planned target volume of median 97.4cc (range, 5.8- 630.1). 3-year overall survival, distant control and local control was 98%, 97% and 84%, respectively. KPS remained stable, with a median of 100% (range 60-100) before and directly after proton therapy. Before PT, 66.1% patients presented with tumor-related toxicity and 40.5% with surgical-related toxicity. After PT, grade 1 or 2 radiation induced acute toxicity was observed in 83.5% of patients. Late toxicity occurred in 36% of patients, including 5.7% grade 3 or 4 toxicity. Patients reported a significantly worse global QoL (47% worsened, p=0.011), QLQ-C30 summary score (32% worsened, p=0.010) and neurological symptom scores (20% worsened, p=0.007) directly after PT, but this improved to baseline level at 1 year follow- up. Future uncertainty improved in 48% (p=0.012), and visual disorder scores in 33% of patients (p=0.026) directly following PT. After 3 years, global QoL was improved in 47% of patients, 24% had an improved QLQ-C30 summary score and 14% improved neurological symptom scores compared to baseline before PT. Conclusion Patients with brain tumors regularly present with tumor- and surgery- related toxicity prior to PT. In this study, PT resulted in an excellent 3-year survival and local control. HRQOL temporarily decreased after treatment. Importantly, these symptoms improved again from one year onwards. These often subtle symptoms of the PRO are sub optimally captured using conventional objective scoring systems, but can greatly influence the daily life and functioning of the patient. This study underlines the importance of additional HRQOL reporting to patients with brain tumors receiving PT. OC-0687 RBE-dependence on LET and fractionation in the rat cervical spinal cord after oxygen ion irradiation L. Hintz 1,2,3 , M. Saager 1,3 , P. Peschke 1,3 , S. Brons 3,4 , J. Debus 3,5,6 , C. Glowa 1,3,5 , C.P. Karger 1,3 1 German Cancer Research Center DKFZ, Medical Physics in Radiation Oncology E040, Heidelberg, Germany ; 2 Heidelberg University, Faculty of Biosciences, Heidelberg, Germany ; 3 National Center for Radiation Research in Oncology NCRO, Heidelberg Institute for Radiation Oncology HIRO, Heidelberg, Germany ; 4 Heidelber Ion Beam Therapy Center HIT, Heidelberg, Germany ; 5 University Hospital Heidelberg, Radiation Oncology and Radiotherapy, Heidelberg, Germany ; 6 German Cancer Research Center DKFZ, Clinical Cooperation Unit Radiotherapy, Heidelberg, Germany Purpose or Objective The cervical spinal cord (CSC) is one of the dose-limiting organs when treating head and neck cancer (HNC) patients with irradiation since an overdose in the spinal cord may lead to irradiation-induced myelopathy, an irreversible and severe side effect. Thus HNC is one of the most relevant indications for radiation treatments with ions. The local effect model (LEM) – actually used for treatment planning in carbon ( 12 C) ion therapy in Germany – predicts the increased relative biological effectiveness (RBE) needed for RBE-weighted dose calculations. Accordingly, uncertainties in the RBE can lead to under- or over- dosages, making it mandatory to validate the predictions by experimental data. As the further increased RBE of oxygen ( 16 O) ions could have a great benefit for treating radioresistant hypoxic tumors and are therefore planned to be implemented at the Heidelberg Ion Beam Therapy

Conclusion Significant target volume and dose reduction to all OARs could be achieved when targeting only individual LNs by use of on-line MRI guidance. This new concept has the promise to achieve highly effective regional RT on an MRI- linac, with potentially lower toxicity for HN patients. The clinical impact of this novel approach is to be investigated in future studies.

Proffered Papers: Proffered papers 34: Particle therapy in CNS tumours

OC-0686 Quality of life and patient-reported outcomes after proton therapy for brain tumors in adults. S. Kroeze 1 , P. Mackeprang 1 , C. De Angelis 1 , M. Walser 1 , A. Pica 1 , B. Bachtiary 1 , U.L. Kliebsch 1 , D.C. Weber 1 1 Paul Scherrer Institute, Centre for Proton Therapy, Villigen, Switzerland Purpose or Objective Proton therapy (PT) is delivered to complex brain tumors to obtain an optimal curative treatment with limited toxicity. Value-based medicine is increasingly important in oncological treatments, particularly when long-term survival is to be expected. This study aims to evaluate health related quality of life (HRQOL) and patient reported outcomes (PROs) in patients treated with PT for brain tumors and compare these data to treatment-related Between 04/2015 and 04/2019 121 consecutive adult patients with intracranial tumors treated with PT at the Paul Scherrer Institute prospectively filled out the EORTC- QLQ-C30 and B20 questionnaires before, during, directly after, 1- ,2- and 3- years following PT. Early and late toxicity was prospectively scored using the Common Terminology Criteria for Adverse Events (CTCAE) score v. 4.03. Clinical outcome and dose-volumetric factors were registered. The median FU was 24 (95% CI 20.9-27.1) toxicity and outcome. Material and Methods

months. Results

Median age was 45.3 (range 18.8-77.7) years. Tumors were mainly located in the skull base (65.2%) and WHO grade I-