ESTRO 37 Abstract book

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ESTRO 37

Purpose or Objective Radiosurgery is a therapeutic approach for the treatment of brain metastases (BMs). Different technological modalities have been used. We draw this phase III trial with the aim to evaluate incidence of symptomatic radionecrosis using gammaknife versus linac-based (EDGE) radiosurgery. Local control and overall survival (OS) were assessed. Material and Methods Patients with up to 4 BMs were enrolled. Inclusion criteria were: KPS ≥70, RPA class I-II, BMs maximum diameter ≤3 cm and/or with a total tumor volume <30 cm 3 . Prescribed dose was 24 Gy or 20 Gy depending on lesion dimension. Clinical outcome was evaluated by neurological examination and MRI. Results From October 2014 to August 2017, 134 patients of the expected 250, for 236 BMs were evaluated. Most common primary was NSCLC (53.7%). Symptomatic radionecrosis was observed in a total of 23 (9.7%) cases of the entire cohort evaluated. In the gammaknife ARM Grade II radionecrosis was recorded in 8 cases and Grade III in 3. In the EDGE ARM only grade II radionecrosis occurred in 12 cases treated. Five local progressions in site of SRS occurred. The median, 6 months- and 1 year- brain distant failure (BDF) were 22.4 months, 11% and 31%, respectively. Median progression free survival (PFS) was 8.7 months, 6- and 12 months PFS were 67.1% and 34.7%. The median, 6 months and 1 year OS were 17 months, 89.3% and 73.3%, comparable in both arms. In univariate and multivariate analysis the volume of BMs influenced radionecrosis rate. Conclusion Gamma-knife and LINAC based SRS for BMs were comparable in terms of LC. In this preliminary evaluation the risk of G3 radionecrosis was greater and earlier in the gammaknife arm. OC-0592 Hypofractionated stereotactic radiotherapy of large brain metastases: analysis of 350 patients P. Ivanov 1,2 , I. Zubatkina 1 , A. Kuzmin 1 , D. Nikitin 1 , V. Krasnyuk 1 , G. Andreev 1 , F. Schepinov 1 1 Radiosurgery- Stereotactic Radiotherapy and General Oncology clinic MIBS, Radiosurgery, Saint-Petersburg, Russian Federation 2 Polenov Russian Scientific Research Institute of Neurosurgery- Branch of Federal Almazov North-West Medical Research Centre, Neurooncology, Saint- Petersburg, Russian Federation Purpose or Objective To analyze radiological and survival outcomes in a large cohort of patients with brain metastases who received hypofractionated stereotactic radiotherapy (HSR) with a focus on short-term and long-term tumor response, complications and mortality. Material and Methods Patients with large brain metastases who underwent HSR between 2010 and 2016 were included in the study. Radiation treatments were performed with Gamma Knife 4C and Perfexion (Elekta AB, Stockholm, Sweden), Cyber Knife (Accuray, Sunnyvale, CA, USA) and linear accelerator TrueBeam STX (Varian Medical Systems, Palo Alto, CA). The median tumor volume was 23.5 cm 3 (from 9.1 to 106.7 cm 3 ). The number of metastases treated with HSR per patient varied from 1 to 6 with a mean of 2. Patients with multiple brain metastases were subjected to a combination of HSR and stereotactic radiosurgery (SRS). A three-fraction stereotactic radiotherapy was applied for irradiation of large brain metastases with the total prescription dose from 24 to 30 Gy at a median of 80% isodose. Radiation schemes were selected depending on the number of metastases, size, location, proximity to critical brain structures, histological type of primary cancer and patient general condition. Following

meningioma patients undergoing a complete resection (Simpson I-III) is superior to 70% when treated with high- dose (60 Gy) RT. The estimated OS-3Y was excellent. Fourteen percent of patients presented with grade 3-4 serious adverse events after RT. OC-0590 Screening MRI for radiation-induced meningioma in childhood cancer survivors with prior cranial RT J. Co 1 , M. Swain 1 , L. Murray 1 , S. Ahmed 1 , N. Laperriere 1 , D. Tsang 1 , D. Hodgson 1 1 Princess Margaret Cancer Centre, Radiation Oncology, Toronto, Canada Purpose or Objective Radiation-induced meningioma (RIM) is a known late effect of cranial radiotherapy. Cranial MRI screening in a high risk population may detect these meningiomas early but currently its value is not well defined. This study describes the outcome of MRI screening among survivors of childhood leukemia who were treated with cranial RT (CRT). Material and Methods The study cohort at risk for RIM was composed of childhood leukemia survivors who received CRT and attended the pediatric aftercare clinic in our cancer centre from January 2005 to February 2017. MRI screening for RIM was implemented in January 1, 2013. The screened group was composed of those who had screening cranial MRI from January 1, 2013 to February 2017. Outcomes of this group were compared with those attending clinic who underwent cranial MRI only for symptomatic presentation, before the implementation of routine screening. We also compared the outcome of RIM with outcomes of 150 randomly selected adult cases of sporadic meningioma seen at our centre. Results 192 childhood leukemia survivors were included in this study, 86 in the screening group, 106 unscreened. Median time from RT to first screening MRI was 25 years (range 11-40 years) and the median number of screening MRIs was 1 (range 1-3). Screening MRI detected meningioma in 15 (17%) screened survivors. In the unscreened group, 17 (16%) had neurologic symptoms leading to an MRI; 9 patients (8.5%) were diagnosed with meningioma. The cumulative incidence of meningioma 25 years after CRT were 6.3% and 3.4% in the screened and unscreened groups respectively (p= 0.09). There were no significant differences in age of detection, tumour size, multifocality, extent of resection, number of atypical and anaplastic histology, or use of adjuvant radiotherapy between screened and unscreened groups. There were 3 patients who had neurologic residual deficits in the unscreened group versus none in among screened patients, but this did not reach statistical significance (p= 0.25). Based on our results, a study of >600 survivors would be required to demonstrate clinically and statistically significant improved outcomes with Screening MRI was able to detect meningioma before becoming clinically apparent. However, we could not demonstrate a significant improvement in the likelihood of total resection or a decrease in morbidity. A larger sample could clarify potential reduction in neurologic sequelae associated with screening. OC-0591 Phase III randomized trial comparing two modalities of RS for brain metastases: Gammaknife vs Linac V. Palumbo 1 , P. Navarria 1 , S. Tomatis 1 , E. Clerici 1 , G.A. Carta 1 , P. Picozzi 1 , P. Mancosu 1 , M. Scorsetti 1 1 Istituto Clinico Humanitas, Radiotherapy, Rozzano Milan, Italy screening. Conclusion