ESTRO 2020 Abstract book

S522 ESTRO 2020

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simultaneously. Statistically significant differences were observed regarding headache (p=0.031) and nausea (p=0.008) with more events in the group treated in parallel. Conclusion Patients who are irradiated for brain metastases and receive PD-1 inhibitors simultaneously have more acute side effects than patients undergoing both treatments but not at the same time. We observed especially more nausea and headache in this patient group. This might be due to the invasion of immune cells to the RT field leading to local reactions like pseudoprogression. To prove this, further analyses are ongoing. Overall, the severity of toxicities was moderate with few grade 3 events. Late side effects were rare and evenly distributed in both treatment groups. We consider the application of both treatments at the same time to be safe and applicable in clinical routine. Additional investigations are needed to determine if the application of RT to brain metastases and ICB simultaneously leads to an improvement of oncological endpoints. PO-0892 Hypofractionated stereotactic radiotherapy for meninigioma, multicentric serie M.P. Sunyach 1 , M. Pernod 1 , C. Carrie 1 , B. Pierre Yves 2 1 Centre Leon Berard, Rhone, Lyon cedex 08, France ; 2 Centre Antoine Lacassagne, Alpes Maritimes, Nice, France Purpose or Objective Introduction: Meningiomas represent 30% of intracranial tumors. Only progressive tumours and/or symptomatic or high-grade have an indication for treatment. For progressive or symptomatic tumours, surgery is the reference treatment. When this is not possible, exclusive radiotherapy (RT) is proposed. Depending on the topography of the meningiomas and their size, there are several radiotherapy techniques. The hypofractionated stereotactic radiotherapy (hSRT) allows to treat larger volumes than SRS while keeping the radiobiological benefit of hypofractionation. This technique is currently available in more and more centres. Local control and tolerance of hSRT are poorly evaluated in the literature. The objective of this series is to analyze the practices of two centres, and also to focus on clinical benefits by analysing the Materials and methods: Our study was retrospective and multicentric (CLB and Nice). We have included patients between 2007 and 2013 for intracranial meningiomas treated with hSRT by Cyberknife. We excluded patients with concomittant cerebral pathologies, particularly in the context of neurofibromatosis. We studied the neurological symptoms before treatment with Cyberknife and their progression throughout the follow-up (taking into account possible aggravations after radiotherapy) as well as tumor Results: 96 lesions were treated, the median follow-up was 4.4 years. The assessment was done for each symptom. We also performed an overall neurological score for each patient and evaluated the evolution of this score at the over time. At the last news this score was significantly improved p<0.0001 (1.8-1). In The 54 patients (56.3%) 95% CI (45.8% - 66.4%) the global neurologic score is improved after radiotehrapy. Patients with exclusive RT have greater benefice compared to patients treated at recurrence or with post operative irradiationp=0.0015. Survival without recurrence was 76% at 5 years. Overall survival was 95.2% at 5 years. Event free survival was 57% evolution of symptoms. Material and Methods control. Results

Material and Methods Patients with newly diagnosed glioblastoma, age years, Karnofsky performance scale (KPS) score ⩽ 60, were enrolled. The total dose of HFRT was 40 Gy/15 fractions. Thirty patients were treated, with a median age of 78 years. Concurrent and adjuvant temozolomide chemotherapy (TMZ-CHT) was administered in 9 (27.3%) and 11 (40.7%) patients received only adjuvant TMZ-CHT. Results The median, 6-month PFS, and 12-month PFS were 39.3%, and 17%, respectively. No increase in steroid drugs was required during radiotherapy treatment and a reduction was possible in 9 (32.3%). Patients with KPS=60, RPA V, MGMT methylated status, neurological status stable or improved after surgery and who underwent HFRT with concurrent and adjuvant CHT, had the better outcome. Conclusion HFRT has proven to be feasible and effective, with limited morbidity, for selected elderly and frail patients with newly diagnosed elderly glioblastoma. The primary objective of this study was not reached in the whole cohort but only in selected patients, who need more aggressive treatment. PO-0891 Application of radiation therapy to brain metastases with parallel or non-parallel PD-1 inhibition M. Trommer 1,2 , S. Marnitz 2 , D. Funken 1 , A. Adams 3 , M. Hellmich 3 , E. Celik 1,2 , J.M. Herter 1,2,4 , J. Morgenthaler 1,2 , M. Kocher 2,5 , D. Rueß 2,5 , M. Ruge 2,5 , C. Mauch 2,6 , J. Werner 2,7 , N. Galldiks 2,7 , C. Baues 1,2 1 University Hospital of Cologne, Department of Radiation Oncology, Köln, Germany ; 2 University Hospital of Cologne, Center for Integrated Oncology CIO, Köln, Germany ; 3 University of Cologne- Medical Faculty, Institute of Medical Statistics and Computational Biology, Köln, Germany ; 4 University of Cologne, Center for Molecular Medicine Cologne CMMC, Köln, Germany ; 5 University Hospital of Cologne, Department of Stereotaxy and Functional Neurosurgery, Köln, Germany ; 6 University Hospital of Cologne, Department of Dermatology, Köln, Germany ; 7 University Hospital of Cologne, Department of Neurology, Köln, Germany Purpose or Objective Immune checkpoint blockers (ICB) targeting the PD-1/PD- L1 axis are an integral component in cancer therapy. They are used both as monotherapy and in various treatment combination concepts. In case of brain metastases, radiation therapy (RT) is frequently added in treatment management. We analyzed acute and late adverse events of patients with cerebral metastases of different tumor types treated with RT and parallel or non-parallel application of ICB. Material and Methods Retrospectively we analyzed treatment related toxicities according to the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 of all patients being treated at our center from 2013 to 2017 with RT to brain metastases and anti-PD-1 therapy simultaneously or with at least 1-month interval between both therapies. All tumor types and RT concepts were included. Adverse events were compared using cross-tables and the Chi-square test with SPSS v. 26. Results 55 patients with 80 brain metastases were analyzed. 31 of those patients were treated in parallel, 24 received both therapies consecutively. Either pembrolizumab (n=36) or nivolumab (n=19) was applied. The most frequently observed side effects in the whole patient cohort were fatigue (31%), pruritus (23%), and nausea (22%). We detected more acute (91 events) than late (6 events) side effects with CTCAE grades from 1-3. Grade 3 events were rare and included only acute side effects and were evenly distributed in both groups (4 and 5 events). In the group of patients treated in parallel, we found 65 acute side effects, compared to 26 in the group not treated

at 5 years. Conclusion

Conclusion: hSRT radiotherapy is a well-tolerated technique. It improves symptoms neurological and those in particular when it is exclusive.