ESTRO 2020 Abstract book

S511 ESTRO 2020

The occurrence of post-operative ischemia after first surgery did not predict the development of post-radiation injury. Presence of prior post-radiation injury at recurrence was associated with less postoperative ischemia after re-resection in patients with a recurrent grade II-IV glioma. No evident spatial relation between post-radiation injury and postoperative ischemia was found. A better understanding of the effects of glioma treatment on the surrounding vascular status might provide more insight in the development of treatment complications in glioma patients.

difference was found for OS between patients initially treated with SRS or WBRT ( p =0.389). The median BMPFS time was 6.9 months (95% confidence interval 4.5 ‒ 8.9). Eight out of 53 patients (15.1%) treated with upfront SRS and 10 out of 21 patients (47.6%) treated with upfront WBRT experienced local failure. Univariate analysis showed that patients who received upfront SRS or had a single BM at diagnosis had longer time to local failure than those who received upfront WBRT ( p =0.004) or multiple BMs ( p =0.02), but no significant differences were found in multivariate analysis. Twenty-eight out of 53 patients (52.8%) treated with upfront SRS, and 11 out of 21 patients (52.4%) treated with upfront WBRT experienced distant brain failure. There is no significant difference in the time to distant failure between upfront SRS and upfront WBRT. Conclusion Patients with BM from TNBC have median OS of 13.3 mo and BMPFS of 6.9 mo. Good KPS and controlled extracranial diseases were independent prognostic factors for better OS. Initial SRS and single BM at diagnosis were associated with longer time to local failure and this may be related to patient selection. Prospective studies of larger numbers of patients with TNBC and different treatments for BMs are needed. PO-0866 The relation between post-radiation injury and postoperative ischemia in diffuse glioma treatment A.T.J. Van Der Boog 1 , J.J.C. Verhoeff 1 , J.W. Dankbaar 2 , T.J. Snijders 3 , P.A.J. Robe 3 1 University Medical Center Utrecht, Radiation Oncology, Utrecht, The Netherlands ; 2 University Medical Center Utrecht, Radiology, Utrecht, The Netherlands ; 3 University Medical Center Utrecht, Neurology & Neurosurgery, Utrecht, The Netherlands Purpose or Objective Cerebral gliomas are often treated with surgery and subsequent (chemo-)radiotherapy. However, postoperative ischemia and post-radiation brain injury, including pseudoprogression and radionecrosis, are frequent complications after intensive treatment (figure 1), occurring in approximately 60% and 20% of the patients, respectively. The injuries can be symptomatic, leading to increased intracranial pressure and/or neurological deficits, and impact the patient’s quality of life. Since both types of lesions appear to have a vascular origin, we This study investigated the relation between postoperative ischemia, defined as diffusion restriction on early postoperative diffusion-weighted imaging (DWI), and post- radiation lesions on follow-up magnetic resonance imaging (MRI) after (chemo-)radiotherapy in a retrospective database of 144 adult cases of WHO grade II-IV gliomas. Post-radiation lesions were investigated with regard to occurrence and location of postoperative ischemia, as well as in relation to the received dose of radiotherapy. Results Incidence of post-radiation injury after first surgery did not differ between patients with and without postoperative ischemia ( P = 0.846). However, postoperative ischemia after re-resection of a recurrent glioma occurred significantly less in patients with prior post-radiation injury, as opposed to absence of post- radiation injury ( P = 0.023) (figure 2). Investigation of the spatial relation between postoperative ischemia and post- radiation injury showed overlap in 10 of 16 patients (62.5%) in the case of first surgery, and no overlap in the single case of re-resection. Planned radiation dose nor EQD2 was significantly related to post-radiation injury in our population ( P = 0.208 and P = 0.323, respectively). In line with literature, post-radiation injury occurred significantly more in patients receiving additional chemotherapy (p = 0.023). Conclusion suspect a correlation. Material and Methods

PO-0867 Risk of Symptomatic Radiation Necrosis Following Stereotactic Radiosurgery for Brain Metastases M. Sayan 1 , B. Şahin 2 , T. Zoto Mustafayev 2 , E.Ş. Sare Kefelioğlu 2 , I. Vergalasova 1 , A. Gupta 1 , A. Balmuk 2 , G. Güngör 2 , N. Ohri 1 , J. Weiner 1 , E. Karaarslan 3 , E. Özyar 2 , B. Atalar 2