Abstract Book

S680

ESTRO 37

Purpose or Objective Recent data show the interest of radiosurgery (SRS), even for patients with multiple brain metastases (BM), in terms of local control and OS. Further data show the interest of repeated surveillance brain magnetic resonance imaging (MRI) after SRS, to treat new BM while patient remains asymptomatic, reducing the cost of care. Based on these, we started in 2014 a brain metastases clinic at Lausanne University Hospital (CHUV). This clinic was created to favor focal treatments (SRS or surgery) on other strategies in patients with brain metastases, in addition to ensuring their strict follow-up. Focal treatments have been proposed for most of patients: 68% radiosurgery and 14% surgery (always followed by a SRS); chemotherapy for 14% and WBRT for 4% of patients. We present the results of 382 individual patients from this single-institutional cohort treated by SRS. Material and Methods 382 consecutive individual patients from all histologies (51% NSCLC, 18% melanoma and 13% breast) were treated 592 times by SRS using CyberKnife (67% of cases) or Gamma Knife (33%) at CHUV since early 2014. All patients were followed with a 3D brain MRI every 2 months after the first treatment (SRS): if new metastases appeared during the follow-up, this triggered a new SRS (if feasible) treatment. Results For patients treated with SRS, the number of metastases treated per patient ranged from 1 to 22, the median PTV volume was 2.1 cc. Median FU was 15.9 months. The 1-year and 2-year OS were 58.7% and 39.6%, respectively. When stratifying patients based on the number of BM at first SRS treatment the 1-year OS was 58.2% for patients with single BM, 67.5% for 2 to 4 BM, 66.7% for 5 to 9 BM and 35.9% for patients with 10 or more BM (p = 0.0021). 25% of patients presented more than 4 metastases at the first episode. The 1-year and 2 year brain-DFS were 25.9% and 11.7% respectively: as local control over treated lesions was over 95%, the brain-DFS was impacted by the appearance of new lesions (that were also treated by SRS). 33% of patients had more than 1 SRS. Salvage WBRT was needed in only 5 patients (1.3%). The incidence of side effects was very low, with less that 3% of patients presenting nausea, dizziness/vertigo or persistent headache after the treatment, and less than 1% presenting seizures or an increase of previous neurological deficits. Less than 3% of patients presented symptomatic radionecrosis during their follow-up. Conclusion The results of this single-institutional cohort show that upfront SRS for patients with brain metastases is feasible, even for patients with more than 3 BM. This treatment is mostly curative for treated lesions, and it can be repeated several times (WBRT is still possible as salvage treatment). This treatment approach in multidisciplinary brain metastases units optimizes the management of patients and could improve OS while obtaining high brain control rates. EP-1226 Therapy of leptomeningeal carcinomatosis in breast cancer patients – a single center experience C. Diehl 1 , J. Ettl 2 , K. Borm 1 , S.E. Combs 1 , M.N. Duma 1 1 Klinikum rechts der Isar- TU München, Department of Radiation Oncology, München, Germany 2 Klinikum rechts der Isar- TU München, Department of Gynaecology and Obstretics, München, Germany Purpose or Objective Leptomeningeal carcinomatosis (LM) with tumor spread along the cranial and spinal meninges can occur in any type of cancer, but breast cancer (BC) is the most frequent solid primary tumor. Up to date intrathecal

methotrexate (i.th. MTX) chemotherapy or whole brain irradiation (WBRT) with or without irradiation of the complete cranio-spinal axis (CSI) are widely used therapy regimes, but there is no standard of care. In this single center analysis, both therapy regimes were compared to each other with focus on survival and graded prognostic assessment (GPA). Material and Methods Clinical files, records and radiologic data were retrospectively reviewed from patients diagnosed with LM and treated at our institution from 2008 up to date for tumor staging, histopathologic tumor features, diagnostic, treatment regimes, clinical performance score (Karnofsky performance index/KPI, graded prognostic score/GPA) and overall survival calculated as time from diagnosis of LM (date of positive lumbar puncture or MRI with signs of LM) until death or last appointment at our institution if date of death was unknown. Tumor burden was estimated by the number of extracranial sites of metastases (ecM1). Results 20 female BC patients treated at our institution (department of radiation oncology, gynecology and hematooncology at Klinikum rechst der Isar, Munich, Germany) were reviewed in this study. 3 patients were hormone receptor negative, including two triple-negative patients. Her2/neu was positive in one patients. 7 patients were diagnosed with LM by positive l umbar puncture (CSF was negative in 6 cases), 13 patients showed signs of LM on cMRI (5 patients had normal cM RI, all of them were treated with i.th. MTX). Mean age at diagnosis of LM was 55 years (35-84 years), mean time between initial diagnosis of BC and occurrence of LM was 71,4 months (4-204 months). One patient received no specific LM therapy and was assigned for best supportive care (BSC), one patient received WBRT at another center and was lost to follow-up. 10 patients were treated with WBRT, 6 patients received i.th MTX (in mean 6 cycles). 2 patients had both i.th MTX and WBRT consecutively. In the i.th MTX group (mean age 62,3 years; 3 of 6 patients with KPI ≤ 60%; in mean ecM1 2,5) average GPA score (LM accounting for >3 mets) was 0,91 (0-2) and mean overall survival (OS) was 4,8 months (1-12 months), in the WBRT group (mean age 51,3 years; 4 of 10 patients with KPI ≤ 60%; in mean ecM1 3,4) mean GPA-score was 0,65 (0-1,5) and mean OS was 3,2 (1-8 months). Those two patients receiving both i.th MTX and WBRT had a mean GPA of 0,5 and OS of 5,5 months (4-7). Conclusion In accordance with several studies survival of LM is poor independent of the treatment modality, in this series there was a slightly advantage for i.th MTX compared to cranial WBRT. However, in the i.th MTX group GPA was higher and tumor burden was lower compared to the WBRT group. Best OS was seen in two patients who received both i.th MTX and WBRT despite a low GPA. EP-1227 Dosimetric Comparison of Simultaneous Integrated vs. Sequential Boost in Radiotherapy for Gliomas T. Nageeti 1 , M.A. Mahfouz 1 , H. Gomaa 1 , M. AlGaoud 1 , R. Zatar 1 1 King Abdullah Medical City -Holly Capital KAMC-HC, Jeddah Oncology Centre, Makkah, Saudi Arabia Purpose or Objective To compare the dosimetric coverage of the Planning target volumes (PTV) and sparing organs at risk (OARs) in volumetric modulated arc therapy (VMAT) technique for high grade glioma using different methods to Boost the tumor bed by sequential boost (SB) vs. simultaneous

integrated boost (SIB). Material and Methods

Non-interventional dosimetric study of seven consecutive cases of high grade gliomas who attended radiotherapy