ESTRO 38 Abstract book

S381 ESTRO 38

GBM (not grade III) and were treated with surgery followed by CRT (temozolomide, TMZ) were included in the analysis. Median age was 60 years (23-79 years) with predominance male gender (61.7% vs. 38.3%). On a multivariant analysis: ischemic heart disease, degree of surgical resection, total radiation dose, number of TMZ cycles, and CRT waiting-time were significant for survival. A significant difference in OS (HR=0.49, p-value=0.002, 95% CI: 0.32-0.78) and PFS (HR=0.51, p-value= 0.003, 95% CI: 0.33-0.79) in the group who were CRT was initiated > 6 weeks after surgery, compared with the other two groups tested, favoring longer waiting times. Conclusion According to our study, a time-gap of > 6 weeks for initiation of CRT after surgical resection was associated with better survival outcome. As our study represents retrospective “real-world data” from a tertiary hospital, the full report of the study analyzes the potential factors and biases that might have influenced our results and have significance in the daily practice. PO-0743 Single dose versus FSRT for brain metastases: a retrospective study. C. De la Pinta Alonso 1 , E. Fernández 1 , M. Martin 1 , R. Hernanz 1 , C. Vallejo 1 , M. Martín 1 , A.B. Capúz 2 , J.A. Rojo 3 , I. Villodre 3 , S. Sancho 1 1 Ramon y Cajal Hospital, Radiation Oncology, Madrid, Spain ; 2 Ramon y Cajal Hospital, Medical Physics, Madrid, Spain ; 3 Ramon y Cajal Hospital, Radiotherapist, Madrid, Spain Purpose or Objective Radiosurgery is increasing being employed for the treatment of brain metastases, both as an adjuvant to surgical resection, and also as a primary treatment modality. The aim of this study is to evaluate the efficacy and tolerability of radiosurgery in patients with brain metastases comparing two different treatment regimens, single-dose radiosurgery(SRS) andfractionated stereotactic radiotherapy(FSRT). Material and Methods Between 2004-2018 we analyzed 97 patients with 135 brain metastases. Fifty-six patients were treated with SRS, and forty-one were treated with FSRT. The median doses were 16 Gy(12-20Gy) for the SRS group and 30 Gy in 5 fractions for the FSRT group. FSRTwas used for large lesions or lesions located near critical structures. Kaplan Meier curves were constructed for overall survival and local control. Results Median age was 61,9 years(32– 89 years). Patients had Karnosfky-performance status>70 in 72,8%. Median survival was 10 months for all patients(1-68). With a median of 10 months no significance differences between overall survival between groups(p=0,21). Local control for all patients was 67%. Local progression-free survival(LPFS) at 6 months and 1-year were 71% and 60%, respectively, for the SRS group and 80% and 69%, respectively, for the FSRT group(p = 0.129). Despite the fact that FSRT was used for large lesions and lesions in adverse locations LPFS was not inferior to SRS. We observed acute toxicities grade 1- 2 consisted of brain edema(22p) and crisis without sequels(3p). Late complications consisted of radionecrosis(3p), post-radiation syndrome(1p), chronic crisis(5p), pan-hypopituitarism(1p) and insipid diabetes(1p). Acute toxicity was more frequently observed in the FSRT-group than in the SRS-group(29% vs. 23%, p=0.63) and chronic toxicity was more frequently observed in the FSRT-group than in the SRS-group(19,5% vs. 7,1%, p=0.11). Brain recurrence occurred in 37,5% and 14,6% FSRT vs SRS-group respectively(p=0.06). Conclusion Because patients treated with FSRT exhibited similar survival times and LPFS rates with a lower risk of toxicity in comparison to those treated with SRS, despite the fact

Results median follow-up was 17 months (range, 4.8-62.3). Very low rates of side-effects developed, including headaches, nausea and dizziness during treatment. No high-grade (grade 3-4) treatment-related toxicity was observed. Local control was 99%. Only one patient, affected by atypical meningioma, had local recurrence 22 months after the end of the treatment. Two pts with atypical and anaplastic meningioma respectively had “out-of-field” recurrence 20 and 8 months after the end of the treatment Conclusion PT is a safe and effective treatment for pts with intracranial meningiomas, and it allows to deliver high local doses even in complex anatomy (as skull-base lesions) while sparing critical OARs PO-0742 The survival impact of the time between surgery and chemo-radiotherapy in Glioblastoma patients O. Kaidar-Person 1 , I. Zur 1 , T. Tzuk-Shina 1 1 Rambam Health Care Campus - Faculty of Medicine, Oncology Institute, Haifa, Israel Purpose or Objective Glioblastoma multiforme (GBM) is the most common primary CNS malignancy. Although multimodality therapy, it is bares grave prognosis. While importance of current treatment protocol is well-known and practiced, it is still unclear what is the optimal waiting time between surgery and the initiation of radio-chemotherapy (CRT). The aim of the current study is to evaluate the impact of the waiting time of initiation of CRT after surgery on disease outcome. Material and Methods After IRB approval, we conducted a retrospective study of all medical records of GBM patients treated at our institution between 2005-2014. Data collected included: demographics, degree of surgical resection, performance status, dates and treatment protocols, and outcome. For data analysis, patients were divided into 3 groups according to the time-gap from surgery to initiation of CRT: < 4 weeks (47 patients), 4-6 weeks (72) and > 6 weeks (84). Univariant and multivariant analysis were performed. Overall survival (OS) and progression free survival (PFS) were analyzed using the Kaplan-Meier method and Cox proportional hazard model. Results A total of 465 high-grade Glioma cases were reviewed, 261 were excluded. Only patients who were diagnosed with