ESTRO 2021 Abstract Book

S49

ESTRO 2021

OC-0076 Meningioma I° involves optical structures: does proton therapy lead to subjective changes in vision? B. Flechl 1 , L. Konrath 2 , E. Hug 1 , C. Lütgendorf-Caucig 1 , M. Achtaewa 3 , M. Pelak 1 , A. Schallerbauer-Peter 3 , J. Zimmermann 4 , M. Sebek 1 , C. Svardal 5 , M. Mumot 6 , U. Mock 7 , R. Konstantinovic 1 , P. Fossati 1 , P. Georg 1 1 MedAustron, medical department, Wiener Neustadt, Austria; 2 MedAustron, clinical studies office, Wiener Neustadt, Austria; 3 MedAustron, clinical studies, Wiener Neustadt, Austria; 4 MedAustron, clinical studies , Wiener Neustadt, Austria; 5 MedAustron, radiation therapy technology, Wiener Neustadt, Austria; 6 MedAustron, medical physics, Wiener Neustadt, Austria; 7 MedAustron, medical department , Wiener Neustadt, Austria Purpose or Objective In addition to local tumor control, the aim of curative radio-oncological treatment is to maintain quality of life. When treating patients with meningiomas that are closely related to optical structures, maintaining visual performance is a particular challenge. The use of proton therapy can reduce the dose exposure of the risk structures immediately adjacent to the tumor. The aim of this study was to review the subjective assessment of the visual performance of patients with meningiomas with involvement of the optical structures before and This study included all patients treated with protons with meningiomas WHO I, whose planning target volumes (PTV) included parts of the optic nerve and/or chiasm. The subjective assessment of visual performance was evaluated using the Visual Disorder Scale (VDS) of the EORTC-BN20 questionnaire. This scale includes values from 0-100, with high values reflecting a high degree of subjective symptom burden and thus subjective visual reduction. The test time points were before the start of therapy, at the end of therapy, and 3,6,12 and 24 months in the follow-up (FU, t1-t6). The visual acuity from externally performed eye tests at baseline and at annual FU was also evaluated. All patients for whom data were available at least 6 months after the end of therapy at the time of the evaluation were included. Results 56 patients (45w/11m) aged 24-82 years (mean±SD=53.9±13.3) were included in the analysis. The treatment dose using protons was 54 Gy(RBE). The mean/D2% dose±SD for the optic chiasm and ipsilateral optic nerve was 43.4±8.9 Gy(RBE)/49.9±7.1 Gy(RBE) and 35.6±11.7 Gy(RBE)/51.7±4.8 Gy(RBE); the mean/D2% dose±SD of the contralateral optic nerve was 18.8±12.1 Gy(RBE)/42.4±14.6 Gy(RBE). A total of 302 data collections were available (t1/t2/t3/t4/t5/t6: n=56/56/48/56/52/34). The mean observation time was 23.6 months. The mean symptom burden largely decreased over time with the following mean±SD values for the VDS: t1 29.8±27.9; t2 25.0±27.9; t3 21.8±26.0; t4 22.2±26.0; t5 21.4±26.2; t6 17.3±23.6 (see graph 1). One year after the end of therapy, the subjective visual performance improved significantly, taking into account a relevant change of at least 20 points (p=0.041, Wilcoxon rank-sum test ). 13 out of 15 patients without symptoms before starting treatment report no worsening with 12mo-FU. In 34 of 37 patients with symptoms at the start of treatment, there was a stability/improvement in the 12mo-FU. The objective eye tests available in 21/52 patients at baseline and at the annual FU confirm the trend towards improved visual acuity (16/21 stable/improved in the annual FU). after proton therapy. Materials and Methods

Conclusion The proton treatment of patients with meningioma WHO I with the involvement of optical structures does not impair subjective visual performance. One year after the end of therapy, there was a statistically significant improvement in the perceived visual performance. OC-0077 High-dose post-operative Protontherapy to improve the outcome of high-grade meningiomas K. Holub 1 , S. Froelich 2 , H. Adle-Biassette 3 , J. Guichard 4 , K. Champeaux 2 , A. Carpentier 5 , K. Mokhtari 6 , L. Feuvret 7 , G. Lot 8 , S. Bolle 9 , C. Alapetite 10 , S. Helfre 11 , F. Goudjil 10 , I. Pasquie 10 , C. Nauraye 11 , R. El Ayachy 11 , V. Calugaru 11 , R. Dendale 11 , H. Mammar 11 1 Institut Curie, France; Universitat de Barcelona, Spain; Spanish Society for Radiation Oncology (SEOR) - CRIS Foundation, Radiation Oncology, Barcelona, Spain; 2 Hôpital Lariboisière , Department of Neurosurgery, Paris, France; 3 Hôpital Lariboisière , Department of Pathology, Paris, France; 4 Hôpital Lariboisière , Department of Radiology, Paris, France; 5 Hôpital La Pitié Salpêtrière , Department of Neurosurgery, Paris, France; 6 Hôpital