ESTRO 38 Abstract book

S678 ESTRO 38

mortality in patients with tumor, and are frequently managed with radiation therapy (RT). The safety of cranial RT in the setting of treatment ICIs has not been established. We aimed to assess toxicity and adverse events (AEs) in a cohort of patients who received cranial RT and were treated with anti programmed cell death- 1(PD-1). Material and Methods We identified 12 patients with advanced solid tumors (10 Non Small Cell Lung Cancer (NSCLC) -83.3%-,1 melanoma- 8.3%- and 1 renal cell carcinoma-8.3%-) with brain metastases, who received cranial RT and were treated with anti PD-1. RT-related AEs were retrospectively evaluated and analyzed according to ICI treatment status, cranial RT type, and timing of RT with respect to ICI. Results We enrolled 12 patients, between July 2017 and May 2018: 7 (58.3%), 2 (16.7%), and 3 (33.3%) patients received stereotactic RT, whole brain RT or both, respectively. 33.3% of patients received more than one stereotactic course . We observed seizures in one patient during whole brain RT who was symptomatic before treatment; Levitaceram dose escalation and mannitol were used to control seizures. We observed only one radionecrosis (8.33%) occurring 2 months after the end of stereotactic RT. We observed no significant difference in acute neurological toxicity between patients who received whole brain RT or stereotactic RT. Additionally, there was no difference in AE rates on the basis of timing of ICI administration with respect to RT. Cognitive evaluation is in full swing. The median follow up was 5 months, but 2 patients (16.7%) died before follow up and 2 (16.7%) haven’t reassessed yet.6 patients (50%) had brain MRI after RT: 2 (33.3%) had brain progression after stereotactic RT , 3 (50%)complete response after stereotactic RT and 1(16.7%) partial response after whole brain RT. 2 patients(16.7%) died before MRI evaluation for extracranial disease progression and 4 patients (33.3%) will have MRI in the next few months . Conclusion Treatment with an ICI and cranial RT was not associated with a significant increase in RT-related AEs, suggesting that use of anti PD-1 in patients receiving cranial RT may have an acceptable safety profile. Nonetheless, additional studies are needed to validate this approach. EP-1232 Hypofractionated RT in very elderly patients (≥ 75 years) diagnosed with GBM C. Cavallin 1 , C. Mantovani 2 , G.C. Iorio 1 , I. Chiovatero 1 , S. Martini 1 , V. De Luca 1 , C. Palladino 1 , M. Levis 2 , F. Franchino 3 , R. Rudà 3 , U. Ricardi 1 1 University of Turin, Department of Oncology- Radiation Oncology, Torino, Italy ; 2 AOU Città della Salute e della Scienza, Department of Oncology- Radiation Oncology, Torino, Italy ; 3 AOU Città della Salute e della Scienza, Department of Neuro-Oncology, Torino, Italy Purpose or Objective Glioblastoma (GBM) is a highly aggressive tumor with a very dismal prognosis. Elderly patients are at poorer prognosis compared to younger ones and in some cases the benefit of hypofractionated radiotherapy (HFRT) +/- temozolomide (TMZ) is questionable. In this study, We aimed to report the efficacy of a HFRT schedule (42 Gy/14 fr) in a very elderly population (≥ 75 years) and to identify any prognostic factor for this critical group of patients. Material and Methods We retrospectively analysed the data of 45 very elderly patients ≥ 75 years affected with GBM, treated at our Institution between 2010 and 2018 with tridimensional conformal radiotherapy (3D-CRT). The median age at diagnosis was 76 years old (range 75-85). All patients underwent a multidisciplinary evaluation before treatment. Thirty-three patients (73,3%) underwent an upfront surgical approach: 17 (38%) underwent a

%) and fatique (19.7 %). There were only 2 >G3 toxicities with one patient developing seizures and one fatal radionecrosis. At the time of analysis, 40 patients are still alive. Median OS from the time of first re-irradiation was 57 months (range 4 – 186 months). When looking at all treatment courses combined up to 58 % of patients had an intracranial controlled disease after any course of radiotherapy. Conclusion Repeated radiotherapy appears both safe and efficient in patients with recurrent primary or secondary brain tumors. There were only few high grade treatment related toxicities. EP-1230 Hippocampal sparing radiotherapy in patients with primary brain tumors (PBT) M. Konopka-Filippow 1,2 , E. Sierko 1,2 , D. Hempel 1,2 , E. Szewczuk 3 , M. Wojtukiewicz 2 1 Comprehensive Cancer Center in Bialystok, Department of Radiotherapy, Bialystok, Poland ; 2 Medical University of Bialystok, Department of Oncology, Bialystok, Poland ; 3 Comprehensive Cancer Center in Bialystok, Department of Physics, Bialystok, Poland Purpose or Objective Radiotherapy (RT) is an integral part of brain cancer treatment in patients with primary brain tumors (PBT), but is also associated with deteriorated cognitive and memory functions.The aim of study was to report a dosimetric profile of contralateral hippocampal sparing (HS) RT for the treatment of PBT. Material and Methods HS RT was delivered in 15 patients with PBT using the volumetric modulated arc therapy (VMAT) technique between May 2016 and February 2018 at Comprehensive Cancer Center in Bialystok, Poland. The medical records and dosimetric parameters of RT plans: volumes of hippocampi, planning target volume (PTV) , mean dose (Dmean), maximum dose (Dmax) , D98% on hippocampus, D2% and Dmean on other organs at risk (OARs) (optic nerves, optic chiasm, lenses, brainstem) expressed as equivalent to a 2-Gy dose (EQD2/2) were analyzed. RT plans were designed in Monaco Treatment Planning System, version 5.11.02, algorithm Monte Carlo Phantom. Results The median age was 55.4 (range 33-72) years and 62.5% were female. Eleven patients (73.3%) had WHO grade III or IV tumor, whereas 4 patients (26.6%) had grade II tumor. The median PTV volume was 428.01 (range 135-800) cm 3 and the median prescribed dose was 60 (range 40-60) Gy. Concurrent chemotherapy was administered to nine patients (60%). Dmean and Dmax to the contralateral hippocampus was 12.64 (range 2.7-40) Gy and 15.87 (range 1,7-51) Gy, respectively. Conclusion Effective HS was made possible with the development of sophisticated RT delivering techniques such as VMAT. The contralateral hippocampus could be effectively spared in patients with PBT via VMAT. Further investigation is needed to qualify patients who will most benefit from HS - RT of the PBT. EP-1231 Immune checkpoint inhibitor and encephalic radiotherapy: Toxicity and Adverse events P. Matteucci 1 , B. Santo 1 , E. Ippolito 1 , P. Zuccoli 1 , G.M. Petrianni 1 , P. Trecca 1 , S. Gentile 1 , M. Miele 1 , S. Palizzi 1 , L. Trodella 1 , R.M. D'Angelillo 1 , S. Ramella 1 1 Università Campus Bio-Medico Roma, Radioterapia Oncologica, Roma, Italy Purpose or Objective Recently, immune checkpoint inhibitors (ICIs) have shown highly promising responses in solid tumors. Intracranial metastases are a common cause of morbidity and