ESTRO 38 Abstract book

S680 ESTRO 38

started second-line chemotherapy or salvage irradiation or its combination. 13 patients with lesions smaller than 11 cm 3 recieved stereotactic radiosurgery with single dose of 15-24 Gy delivered with CyberKnife or Novalis (6 MeV LINAC). 69 patients with bigger tumors (8 – 48 cm 3 , median volume – 12.7 cm 3 ) were irradiated with 3 to 7 fractions every day or every other day up to total dose of 21 – 39.5 Gy with CyberKnife. 48 patients with large lesions (63 – 382 cm 3 , median – 213 cm 3 ) received 54-60 Gy in 30 fractions with Novalis or Primus (6 MeV LINAC). Results Mean follow-up was 13.3 months. Mean time from salvage irradiation to second progression was 6.2 months, mean overall survival after salvage irradiation was 18 months. Preliminary results showed better survival in patients received bevacizumab-based chemotherapy. In 12 of 152 irradiated lesions (8%) clinically significant radiation necrosis developed, all were successfully treated with bevacizumab. Conclusion salvage irradiation with bevacizumab is an appropriate option for non-invasive treatment for first progression of supratentorial glioblastoma. EP-1235 Response to re-RT helps deciding dose and predicts survival in Diffuse Intrinsic Pontine Glioma J. Manjali 1 , T. Gupta 1 , J. Goda Sastri 1 , G. Chinnaswamy 2 , V. M Patil 3 , R. Krishnatry 1 1 Tata Memorial Hospital, Radiation Oncology, Mumbai, India ; 2 Tata Memorial Hospital, Paediatric Oncology, Mumbai, India ; 3 Tata Memorial Hospital, Medical Oncology, Mumbai, India Purpose or Objective Retrospective review for re-irradiation(reRT) in Diffuse Intrinsic Pontine Glioma (DIPG). Material and Methods Retrospective review of patients who underwent reRT since April 2016. The demographic, clinical and treatment details (descriptive statistics) are reviewed. The outcomes (progression-free survival; PFS, Overall Survival; OS: using Kaplan Meier and Log-rank test) and steroid use rates (descriptive statistics) is determined. OS difference for non-responders vs responders on reRT (at 10 th -15 th fraction clinical improvement determining total reRT dose <30.6 vs 39.6-45Gy respectively) using log-rank test. Results All consecutive 17 patients who received reRT were included. Their median age-at-initial diagnosis was 8 years, mean Lansky play-performance scale (LPS) of 65, diagnosed with >2/3 clinical criteria + all radiological criteria (100%) and received initial radiotherapy (RT) 54Gy/30# using 3DCRT resulting in >50% clinical improvement in all patients. The median PFS post-RT was 9.8 months (m). The progression defined as clinical and radiological criteria of diagnosis; all patient had >2/3 clinical criteria where five (29.4%%) satisfied all three, mean LPS of 60 and mean post-RT time: 9.2 (4-20.5) m (Fig 1). ReRT was done using 3DCRT in all but one patient (IMRT) to a dose ranging 30-45 Gy. Four patients received <30Gy while rest between 39-43.2Gy. Four patients who received <30Gy, three either deteriorated or did not show any clinical improvement at 10 th -15 th fraction (18-27 Gy) despite suitable steroid doses, while one had extensive infiltrative disease limiting the reRT dose (30.6Gy). Remaining 13 patients showed clinical improvement mild to modest and were continued to pre-decided clinician dose (39.6-45Gy). The patient with extensive disease received 30.6Gy also showed good clinical improvement at the end of reRT (40%). The steroid dependency was reviewed in all 13 responders; all were on steroids at the time of reRT initiation, 46.2% were completely off, 38.5% were tapering 41.7% at the end of reRT. Later at one- month post reRT, 61.5% were able to get completely off

approach utilizing 2 co-planar full arcs 10X FFF (Flattening Filter Free) VMAT. The aim of this study was to review SRS treatment delivered via HyperArc in the Beatson Cancer Centre to determine if further optimization was achieved. Material and Methods We reviewed data on the first 36 patients treated using HyperArc planned SRS from October 2017 to September 2018, compared to a cohort of 105 patients treated with SRS with the previous technique. For treatment planning GTV was defined as the edge of the targeted contrast enhancing lesion on fused CT/MRI images. The PTV (there was no CTV) was generated by geometrically expanding the GTV by 2mm. Treatment was prescribed to the 80% isodose line. The evaluated parameters for PTV were dose, volume, number of lesions and gradient index (GI). Clinical records were reviewed to obtain information on age, gender, histology and adverse events reported within one week of SRS. Results 36 patients were identified. Median age was 64 and 58% were female. Primary sites were 47% lung, 24% breast, 13% renal, 8% melanoma and 8% others. The most frequent radiosurgical dose delivered to the isocentre was 20Gy (58%) followed by 16Gy (31%). 75% had a single lesion, 17% had 2 lesions and 8% had 3 or more lesions treated. The median GI for single metastases was 2.98 (range 2.48- 3.81) compared to a median GI of 3.47 (range 2.58-4.87) for the previous cohort (p<0.01). Median GI for multiple metastases was 3.33 (range 2.35-3.95) compared a median GI of 4.06 (range 2.76-5.17) for the previous cohort (p<0.01). The median PTV was 4.69cm3 (range 0.45-16.74) compared to 6.0cm3 (range 0.46-28.63) for the previous cohort. The only reported toxicity was one patient who had a seizure post SRS. Treatment response was assessed using MRI at 6 weeks and was similar for the 2 cohorts. Conclusion For patients with brain metastases, treatment with SRS delivered via HyperArc planning results in better conformity compared to the previous treatment planning system, with a more rapid fall-off in dose outside the treated lesion reducing the brain volume receiving significant dose. With the increasing use of SRS to treat patients with multiple metastases, this will potentially reduce the morbidity of the treatment. EP-1234 Salvage radiotherapy and radiosurgery for first progression of supratentorial glioblastoma. K. Nikitin 1 , A. Belyashova 1 , A. Golanov 1 , S. Zolotova 1 1 Burdenko Neurosugical Institute, Department of Radiation Oncology, Moscow, Russian Federation Purpose or Objective radiosurgery, hypofractionated and conventional fractionated irradiation was delivered for patients with first progression of supratentorial primary glioblastoma in Burdenko Neurosurgical Institute in 2009-2018. Authors presented a retrospective analysis of clinical data. Material and Methods 130 patients (74 man and 56 women) with histologically confirmed primary glioblastoma (NOS – 115, IDH-wild type – 15 patients) were included in the study. Patient age was 18 – 74 years, mean age was 46 years. All patients underwent tumor removal (total, subtotal or partial) followed by conformal radiotherapy (58-63 Gy in 29-33 fractions) to primary tumor site with temozolomide. After completion of radiotherapy all patients received adjuvant chemotherapy with temozolomide. Mean time from completion of radiotherapy to first progression was 9.3 months. First progression as single growing lesion in primary tumor region (locally) was observed 102 (78.5%) patients. Single distant new lesion in brain parenchyma with absence of progression in primary site had 17 (13%) patients. Multifocal progression (multiple new lesions) occurred in 11 (8.5%) patients. At the time of progression patients