ESTRO 37 Abstract book

S664

ESTRO 37

EP-1188 Repeat Radiosurgery for new brain metastases allows avoidance of whole-brain radiation therapy C. Fritz 1 , K. Borsky 1 , S. Frei 1 , L.S. Stark 1 , S. Tanadini- Lang 1 , S.G.C. Kroeze 1 , J. Krayenbühl 1 , M. Guckenberger 1 , N. Andratschke 1 1 University Hospital Zürich, Department of Radiation Oncology, Zurich, Switzerland Purpose or Objective Stereotactic radiosurgery (SRS) is the preferred primary treatment option for patients with a limited number of asymptomatic brain metastases. In case of a central nervous system (CNS) oligo-progression after initial SRS the optimal salvage treatment is not well defined. Within this retrospective analysis, we investigated the feasibility of repeated courses of SRS to defer Whole- Brain Radiation Therapy (WBRT) and aimed to derive prognostic factors for patient selection. Material and Methods From 2014 until 2017, 61 patients have been treated with multiple courses of SRS at our institution. Treatment was delivered as single fraction (18 or 20Gy) or hypo- fractionated (6 fractions with 5Gy) radiosurgery prescribed to the 80%-isodose line. Regular follow-up included clinical examination and contrast-enhanced cMRI at 3-months intervals were performed. Results Overall 61 patients received a median of 2 (range: 2-5) repeated courses of SRS for a total of 287 brain metastases during the observation period. Currently, first analysis of 23 consecutive patients treated between 2014 and 2016 with a median follow-up of 12 months (range: 4- 25.5 months) is available. A median number of 1 lesion (range: 1-13) per course and a total of 4 (range: 2-14) metastases per patient over time were treated. The median interval between repeat SRS courses was 4.5 months (range: 0.8-18.5 months). Median tumor volume was 0.65cm 3 (range: 0.1-32.5cm 3 ). A local control rate of 90% (95%CI: NA) was observed at 1 year independent of treatment course. Median time to out-of-field-brain- failure was 3 months (95%CI 2-4 months). WBRT as a salvage treatment was performed in only 5 of 23 patients (21.7%) median 6.6 months (range: 5.5-10 months) after the first course of SRS. 5 of the 10 deceased patients had died of neurological death, 3 of them had received WBRT previously. Median overall survival (OS) was 22 months (95%CI: NA). No grade 4 or 5 acute or late toxicity occurred, whereas acute and late toxicity grade 3 was observed in only 3, or 2 patients respectively. We will present the analysis for the full patient dataset (n=61 pts., n=287 metastases) at ESTRO 2018. Conclusion Although retrospective in nature, our series provides encouraging evidence that brain metastases amenable to SRS can be salvaged with repeat SRS in selected patients providing excellent local control with acceptable toxicity. With a promising OS, potentially neurotoxic WBRT could be avoided in a relevant proportion of these patients EP-1189 A systematic review on neurocognitive impairment in hippocampal sparing radiotherapy G. Zanirato Rambaldi 1 , S. Guerri 1 , G. Siepe 2 , M.A. Sumon 3 , A.F.M. Kamal Uddin 3 , G. Macchia 4 , F. Deodato 4 , M. Ferro 4 , S. Cilla 5 , A. Pierro 6 , G.P. Frezza 7 , A.G. Morganti 2 , S. Cammelli 2 1 Radiology Department- Department of Experimental- Diagnostic and Specialty Medicine - DIMES, University of Bologna- S.Orsola-Malpighi Hospital-, Bologna, Italy 2 Radiation Oncology Center- Department of Experimental- Diagnostic and Specialty Medicine - DIMES, University of Bologna- S.Orsola-Malpighi Hospital, Bologna, Italy 3 Radiation Oncology Department-, United Hospital Limited- Gulshan, Dhaka, Bangladesh

coverage of plans performed with one shot was 99.9% (92-100%) with two shots 99.7% (95-100%), mean selectivity was 0.25 (0.001-0.63) in one isocenter plan and 0.35 (0.07-0.78) in two isocenter plan. Mean gradient was 3.2 (0.85-8.10) and 3.2 (2.11-9.8) for one isocenter and two isocenters plans, respectively. We observed a statistically significative better coverage in one shot plans (0.9995 vs 0.9968, p=0.0001), on the other hand selectivity was significantly better in RS treatment delivered with two shots (0.2494 vs 0.3546, p=0.0001). At one month the majority of BMs were controlled (96.4%), local control decrease with the time in particular it was 95.1%, 81.8% and 95.1% at 3, 6 and 9 months respectively. Considering demographic and disease features breast histology correlated with a poorer local control (p=0.0001) than other histologies at 3 and 6 months MRI, a GPA > 3 was predictive of local failure (p=0.018) at 9 months MRI . Comparing the local control of the BMs treated with one respect to two shots we found that patients treated with one shot had a better outcome (absence of progressive disease) at one month (1.0% vs 11.6% p=0.0001) and six months (5.9% vs 20.7%, p=0.026) compared to BMs treated with two shots. Conclusion Our study shows that in case of a BM with a diameter inferior to 10mm treated with GKRS, the use of a single shot results in a better coverage and a better local control at one and three months. This last results is probably due to the higher conformity the steeper dose gradient offered by the GK. GPA score and histology are confirmed important prognostic factors affecting clinical outcome of brain metastases patients. EP-1187 Reirradiation using 3DCRT in recurrent brain gliomas: Survival and prognostic factors B. Parkam 1 , K. Anvari 1 , M. Silanian toosi 1 1 Omid Hospital, oncology, Mashad, Iran Islamic Republic of Purpose or Objective To assess the outcomes of reirradiation using conformal 3D-radiotherapy in recurrent brain gliomas. Material and Methods This cohort was performed on patients with gliomas which recur or progress after primary chemoradiation and adjuvant temozolomide. Inclusion criteria consisted of ECOG≤2 and PFS/DFS≥6 months. Patients with history of poor controlled diabetes mellitus and hypertension, brainstem or optic chiasma lesions, and near total surgical resection were excluded. 3DCRT was used for irradiation which GTV contoured as enhancive regions. PTV was considered as GTV+2 cm. High energy linear accelerator (6-15 MV) was used. Results Total, 34 patients were enrolled. The daily dose was 1.8 Gy per fraction up to a median dose of 43.9 Gy. Most patients experience at least partial clinical improvement (55.9%) and stable disease in imaging (41.2%). The median OS from the beginning of reirradiation was 17 months . In patients with ECOG performance state 0 or 1 ,the median OS was 35 months and for ps 2 or 3 , median OS was 11 months.p=(0.15). In irradiation dose ≤ 45Gy the median OS was 9 months and in dose≥45Gy the median OS increased to 17 months.P=( 0.51).Other prognostic factors were evaluated: Temozolamide adminstration Vs no Temozolamide with median Os 17vs 5. p=(0.43). Interval ≤ 24 month between primary RT and reirradiation Vs interval ≥24 month , median OS was 5 month vs 18 month.P=(0.19) Conclusion Reirradiation is a tolerable and beneficial treatment option in patients with recurrent brain gliomas accompanying with improvement in survival.