ESTRO 2022 - Abstract Book

S990

Abstract book

ESTRO 2022

Radiotherapy (RT) is already performed to treat primary brain tumors; however, the effect of repeated RT for recurrent tumors has not been fully explored. The aim of this study is to determine the efficacy of re-irradiation in recurrent glioblastoma. Materials and Methods Between November 2019 and September 2021, 30 patients affected by recurrence of high grade glioma were evaluated and treated with re-RT. Stereotactic radiosurgery (SRS) and hypo-fractionated stereotactic radiotherapy (HSRT) were performed using Volumetric Modulated Arc Technique (VMAT). Results At diagnosis, the median age was 54 years (range 36-76) and median KPS was 80% (range 50-90%). All patients underwent to surgical procedures. Twenty-one patients (70%) had RPA class ≤ IV. Histological diagnosis in one case was oligodendroglioma, 24 patients (80%) were affected by glioblastoma, including 3 cases of multifocal form, and 5 (17%) by anaplastic astrocytoma. In 40% of cases, MGMT was unmethylated and, in 80% of cases, IDH was wild type. All patients underwent to adjuvant RT with concomitant TMZ, with different fractionation approaches: 9 (30%) received hypofractionated RT and 21 (70%) received conventional fractionated RT. The median time occurred between surgical procedure and RT was 8 weeks (range 2-18). The median time occurred between adjuvant RT and disease recurrence was 8 months (range 2-27). At the time of disease recurrence, all patients underwent to re-irradiation receiving SRS-HSRT with a median dose of 24 Gy (range 18-36 Gy) and median fractions of 5 (range 1-6). At a median follow-up time from recurrence of 13 months (range 3-56 months), 10 patients (33%) were alive: 2 (20%) with partial response disease, 7 (70%) with stable disease and 1 (10%) with progression disease out-field. During follow-up, 9 patients with out-field progression disease and good performance status underwent to third re- irradiation, with a median dose of 21 Gy (range 14-27 Gy) and median fractions of 3 (range 1-5). No acute or late neurological side effect grade ≥ 2 were reported. No case of radio-necrosis was detected. In all cases, prophylactic steroid therapy was administrated. One patient experienced, after second surgery and during Regorafenib, dehiscence of the surgical wound. In 3 cases, Grade 2 distal paresthesia was reported. Grade 3-4 hematologic toxicity occurred in 7 cases. Three case of Grade 5 toxicities were reported: 2 septic events and 1 thrombo-embolic event. The median OS after recurrence was 9.8 months (95%CI 7.06-12.13) and 1-year OS was 29% (95%CI 11.4-49.2%). No relevant clinical deteriorations in term of performance status were described. Conclusion Re-irradiation for patients affected by recurrent glioblastomas should be considered for its safety and feasibility. In this setting of patients with a poor prognosis, a gain, even if modest, in term of OS, without affecting the patient's quality of life, it could be favourable. An evaluation in a larger number of patients is needed to obtain more solid data. J. Pattanaik 1 , V. Pareek 2 , M. Barthwal 2 , S. Sanyal 1 , S. Mandal 1 , D.V.S. Praveen 1 , S. Pandey 1 , G. Shyam 1 , M.S. Tanwar 1 , D. Bora 1 , S.K. Samala 1 , S. Nirala 1 , A. A 1 , V. Ghosh 1 , A. Ravi 1 , A.P. Solanki 1 , R. Sisodiya 3 , D.N. Sharma 1 , S. Gupta 1 , H. K P 1 1 IRCH, AIIMS, Radiation Oncology, New Delhi, India; 2 National Cancer Institute, AIIMS, Radiation Oncology, New Delhi, India; 3 IRCH, AIIMS, Radiation Oncology, New Delhi, India Purpose or Objective Liponeurocytoma develops mainly in adult patients within the posterior fossa and it has been categorized as a benign grade II tumor. It is characterized by the presence of neuronal and variable astrocytic differentiation with foci of lipomatous distinction. The rarity has led to no consensus guidelines for the management and thus, the aim of this study was to analyze the literature to create treatment guidelines. Materials and Methods PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed to search existing online databases between January 1, 1990 and December 31, 2020. A systematic search on PubMed and Google scholar was done and an individual patient data analysis was carried out. Results A systematic review and individual patient data analysis of the literature found 103 patients (73 male, 30 female) with liponeurocytoma with most common site of presentation being the posterior fossa (86.1%). The mean Ki-67/MIB-1 proliferation index was 3.56%. After a median follow-up of 58 months, the tumor recurrence rate was 18.9% among the patient cohort. Tumor recurrence was found to be significantly higher among those who did not receive Radiation therapy (p<0.001). Complete Tumor resection was seen in 70.5% and tumor recurrence was after median of 72.5 months favouring the addition of post operative radiation therapy especially in incomplete resection (p=0.012). Conclusion Liponeurocytomas are rare benign tumors, occurring mainly in the cerebellum. The therapy of choice is surgery. Postoperative radiotherapy seems to decrease the risk of tumor recurrence and should be offered to the patient. PO-1168 Systematic Review and Individual Patient data in Lipoid Neurocytoma - Impact of Radiotherapy

PO-1169 IMPACT OF RECURRENCE PATTERN IN PATIENTS UNDERGOING A SECOND SURGERY FOR RECURRENT GLIOBLASTOMA