ESTRO 2023 - Abstract Book

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ESTRO 2023

Results Hypofractionated and Intensified Radiotherapy was well tolerated. 90 % of the patients finished the treatment All the breaks during radiation treatment were produced by the disease. On follow-up MRIs, compatible changes due to treatment /radionecrosis, unable to rule out progression, were observed in 84% of biopsied patients. Overall Survival was 15.5 mounths (2-66 m).

21 patients with fractionation < 2.5 Gy OS was 13.1 months. 30 patientes with fractionation ≥ 2.5 gy, OS was 17.2 months

Conclusion Hypofractionated and intensified radiotherapy improves OS in patients with nonsurgical GM, compared to conventional treatment (Stupp ). This treatment doubles the overall survival in this group. We recommend fractionation ≥ 2.5 Gy/day.

PO-1148 Transitioning from conventional photon therapy to proton therapy for primary brain tumors

P. Munck af Rosenschold 1 , H. Ek 2 , I. Fagerström Kristensen 2 , L. Stenberg 3 , S. Kinhult 2 , H. Benedek 1 , S. Ek 4 , S.A. Engelholm 5 , S. Engelholm 2 1 Lund University and Skåne University Hospital, Hematology, Oncology and Radiation Physics, Lund, Sweden; 2 Skåne University Hospital, Hematology, Oncology and Radiation Physics, Lund, Sweden; 3 Skåne University Hospital, Radiology, Lund, Sweden; 4 Lund University, Physics, Lund, Sweden; 5 Rigshospitalet, Oncology, Copenhagen, Denmark Purpose or Objective Proton radiation therapy (PT) is increasingly selected over photon radiotherapy (XRT) in treatment of low-grade gliomas patients (LGG), due to superior radiation dose-sparing of brain tissue. In this single-institution retrospective study we investigate the influence on treatment planning practices and treatment outcomes, including pseudo-progression (PsP) and survival, for LGG by the introduction of PT. Materials and Methods Adult patients with grade 2-3 glioma consequtively treated with PT or XRT from May 2012 to December 2019 were included. Tumor characteristics and treatment data were collected. The groups treated with PT and XRT were compared regarding treatment characteristics, side effects, occurrence of PsP and survival outcomes. Results Out of 143 patients meeting the inclusion criteria, 44 were treated with PT, 98 with XRT and one with mixed PT+XRT. The patients receiving PT were younger, had a lower tumor grade, more often oligodendrogliomas and received a lower mean brain and brainstem dose. PsP was observed in 21 out of 126 patients, with no difference between XRT and PT (p=0.38). The rate of fatigue in immediate connection to RT (<3 months after) was higher for XRT than for PT (p=0.016). The PT patients had a significantly better PFS and OS than the XRT patients (p=0.025 and 0.035). Progression-free survival and overall survival data are shown in Figure 1. Higher average dose to both brain and brainstem was associated with inferior