ESTRO 2021 Abstract Book

S50

ESTRO 2021

La Pitié Salpêtrière , Department of Pathology, Paris, France; 7 Hôpital La Pitié Salpêtrière, Institut Curie, Department of Radiation Oncology, Paris, France; 8 Fondation Rothschild , Departament of Neurosurgery, Paris, France; 9 Institut Gustave Roussy, Institut Curie, Radiation Oncology Department, Villejuif, France; 10 Institut Curie, Radiation Oncology Department , Paris, France; 11 Institut Curie, Radiation Oncology Department, Paris, France Purpose or Objective To evaluate and confirm the effect of the high-dose conformational Proton therapy on local control (LC) and overall survival (OS) of high-grade meningiomas (HGM). Materials and Methods A total of 104 consecutive patients with HGM [WHO grade II (n = 84) and WHO grade III (n = 20)], treated with postoperative standard Proton beam (PB) component alone (n = 72) or with Proton and photon beams (PhB) components (n = 32) at the Institut Curie – Orsay Protontherapy Center from November 1996 to March 2020 were retrospectively reviewed. The total dose was 68.4 Gy RBE in 38 fractions with Proton component alone (n = 72) or with two components (n = 32): Protons (34 Gy RBE/19 fractions) and Photons (34 Gy/19 fractions). The median age was 61.7 years (range: 22.0-79.8) and the sex-ratio was 1.2 [Male (n=47); Female (n=57)]. Seventeen patients had only one surgery and 87 patients had multiples surgeries (n ≥ 2). Gross tumor resection (GTR) was obtained in 24 patients and for all others (n = 80) the resection was subtotal (STR). The median follow-up was 39.4 months (range 1.2-225.8). Local control (LC), progression-free survival (PFS), overall survival (OS), meningioma-related survival (MRS) and 3-year and 5-year survival rates were evaluated by Kaplan-Meier method. Additionally, the outcomes of patients treated with exclusive PT vs. PT-photons were compared. All post-RT clinical late toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 5.0 (CTCAE v5.0). Results At 5 years the OS, MRS and PFS rates were of 71.2%, 82.7% and 78.8%, while 3-year rates were of 84.0%, 82.0% and 85.0%, respectively. Patients treated with exclusive PT (n=72) lived longer with estimated median OS of 124.3 vs. 80.3 months in PT-photons cohort (n=42, p=0.044). Late toxicity was observed in 55 patients (52.9%), all graded 1-3. Conclusion Adjuvant PB was more effective in HGM, showing high local control and survival rates with low toxicity. Patients treated with exclusive PB presented better outcomes than those treated with combination of protons and photons. OC-0078 Impact of surgery and PET-guided radiotherapy in therapy management of cavernous sinus meningioma I. Hadi 1 , A. Biczok 2 , N. Terpolilli 2 , J. Thorsteinsdottir 2 , R. Forbrig 3 , N.L. Albert 4 , P. Yanchovski 1 , B. Zollner 1 , R. Bodensohn 1 , S. Corradini 1 , P. Bartenstein 4 , C. Belka 1,5 , J. Tonn 2,6 , C. Schichor 1 , M. Niyazi 1,5 1 LMU Munich University Hospital, Radiation Oncology, Munich, Germany; 2 LMU Munich University Hospital, Neurosurgery, Munich, Germany; 3 LMU Munich University Hospital, Neuroradiology, Munich, Germany; 4 LMU Munich University Hospital, Nuclear Medicine, Munich, Germany; 5 German Cancer Consortium (DKTK), Radiation Oncology, Munich, Germany; 6 German Cancer Consortium (DKTK), Neurosurgery, Munich, Germany Purpose or Objective Functional preservation in patients with WHO grade I meningioma involving the cavernous sinus (CSM) is crucial for adequate tumor control. Concise data on the functional outcome of an interdisciplinary, multimodal treatment concept are scarce. Therefore, we analyzed functional outcome and long-term tumor control in CSM patients following maximal safe resection (MSR), fractionated stereotactic radiotherapy (FSRT) or a combination of them. Materials and Methods Patients with WHO°I CSM treated between 2003 and 2017 were included in this retrospective study. Prior to FSRT, a 68 Ga-DOTATATE PET/CT was performed for radiation planning. Progression-free survival (PFS) was analyzed using the Kaplan-Meier method and the log-rank test was performed to test differences between the groups. Cranial nerve function including visual acuity and visual field were analyzed at baseline and during follow-up. Results Eighty-five patients matched the inclusion criteria. Following tumor board recommendation, MSR alone was performed in 48 patients (group A), MSR followed by FSRT in 25 patients (group B), and FSRT alone in 12 patients (group C) (Fig.1) . Indications for MSR were large tumors and compression of the optic nerve. Intracranial tumor volumes were higher in A and B compared to C (median 9.2/10.8/4.3ccm for A/B/C, p=0.023). Median follow-up was 47/46/45 months in group A/B/C. Tumor recurrence was observed in 18 patients (37.5%)/0/0 of group A/B/C. PFS at 5-years was 55.7%, 100%, and 100% in A/B/C (p<0.001) (Fig.2) . Optic nerve compression was more common in A (91.7%) and B (84.0%) than in C (16.7%), p<0.001. Post- therapeutic new onset or deterioration of double vision was observed in 29 % (A), 17 % (B) and 0% (C).