ESTRO 36 Abstract Book

S611 ESTRO 36 2017 _______________________________________________________________________________________________

EP-1130 Hippocampus Dosimetry in patients treated with Stereotactic Radiosurgery for Brain Metastases N.S. Iqbal 1 , J.R. Powell 1 , D.W.O. Tilsley 1 , A. Bryant 2 , A.E. Millin 2 , D. Lewis 2 , J.N. Staffurth 1 1 Velindre Cancer Centre, Department of Clinical Oncology, Cardiff, United Kingdom 2 Velindre Cancer Centre, Department of Physics, Cardiff, United Kingdom Purpose or Objective Brain metastases occur in 20-40% of patients with cancer and common primary sites include lung, breast, kidney and melanoma. Traditionally, whole brain radiotherapy (WBRT) has been the mainstay of treatment. Stereotactic radiosurgery (SRS) has demonstrated improved survival, better quality of life and neurocognitive function (NCF) for patients with 1-3 brain metastases and high functionality. Despite the precision of SRS, a significant proportion of patient experience decline in NCF after the treatment: 63.5% of patients undergoing SRS alone had neurocognitive decline at 3 months (Brown et al., 2016). The hippocampus (HC) has been implicated in NCF impairment following radiation as well as other disease processes such as dementia. The tolerance dose of the HC is unclear for single fraction SRS treatment. In a study of fractionated radiotherapy, a dose of more than 7.3 Gy delivered to >40% of the bilateral HC is associated with significantly higher NCF impairment (Gondi et al., 2011). In animal studies, doses as low as 2 Gy have shown evidence of increased cell apoptosis in HC (Acharya et al., 2010). Material and Methods At Velindre Cancer Centre, Cardiff patients with 1-3 brain metastases with WHO performance status 0-2 are treated with SRS. A retrospective review of all patients treated with SRS without WBRT was performed over 1 year (January 2015 - Januay 2016). Patients were identified using electronic database. We studied dose delivered to hippocampi in our patient population. Bilateral hippocampi were outlined manually according to RTOG 0933 atlas (Gondi et al., 2010) and dose volume histograms were recreated using iPlan RT Dose 4.5, a BrainLab software. Results 30 patients were treated with SRS without WBRT in 1 year. Mean age was 61. The most common primary site was lung (12) followed by kidney (7) and melanoma (4). 19 patients had a single metastasis. 70% (n.21) patients were alive for more than 6 months after SRS; median survival was not reached. Dmax (dose to 0.1cc of the HC) was >5Gy in 8 and 2-4.9 Gy in 12patients. 6 patients received >5 Gy and 8 patients received 2 - 4.9 Gy to 50% of the HC. A major factor influencing high HC dose was the location of the tumour. Metastases located in the temporal and medial parietal lobes and cerebellum were associated with Dmax >5Gy. Objective neurocognitive assessment was not attempted in this study due to the challenges of collecting such data retrospectively and the known confounding factors including steroid and systemic anti-cancer therapy use. Conclusion We have identified a considerable proportion of patients receiving significant radiation dose to the HC. Overall survival of patients is in line with previously published studies. Prospective studies measuring NCF with SRS treatment should also investigate doses to HC in order to determine dose effect relationship and establish dose tolerance for HC in SRS. EP-1131 Evaluation of overall survival following SRS for non-small cell lung cancer brain metastases A. Keller 1 , S. All 1 , H. Patel 1 , C. Sherrill 1 , B. Dumas 1 , M. Mejia 1 , N. Ramakrishna 2 1 University of Central Florida, College of Medicine, Orlando, USA

Conclusion Our study shows that SRT and WBRT-SIB offer a good LC and OS, without significant differences. Probably these data maybe due to the baseline patients selection and size simple therefore we are analyzing QoL and neurocognitive function of survivor patients to understand the global impact of these two modalities of treatments. EP-1129 Fractionated stereotactic radiotherapy for the treatment of cavernous sinus meningiomas I. Tovar Martin 1 , P. Vargas 1 , M. Zurita 1 , R. Guerrero 1 , E. Saura 1 , J.L. Osorio 2 , A. Horcajadas 3 , J. Busquier 4 , C. Prieto 1 , S. Rodríguez 1 , A. Ruiz 1 , R. Ching 1 , J. Expósito 1 , R. Del Moral 1 1 Virgen de las Nieves University Hospital, Radiation Oncology, Granada, Spain 2 Virgen de las Nieves University Hospital, Physics, Granada, Spain 3 Virgen de las Nieves University Hospital, Neurosurgery, Granada, Spain 4 Virgen de las Nieves University Hospital, Neuroradiology, Granada, Spain Purpose or Objective The aim of this retrospective study is to report the results obtained with this technique at our institution in terms of local control, toxicity and clinical situation at the end of the study Material and Methods From April 2005 to December 2014, 54 patients with cavernous sinus meningiomas have been treated. 53,5% of meningiomas were located in the right cavernous sinus, 41,9% in the left cavernous sinus, and 4,7% were bilateral. The median age was 60 years (interquartile range (IQR): 50-66), 76,7% women and 23,3% men. 23,3% of patients were operated before the treatment. The mean dose of radiation was 50 Gy in 25 fractions of 2 Gy per day, given five days per week over 5 weeks. Most cases were treated using a LINAC accelerator with 1 isocenter (97,6%) and 8 arcs of treatment (32,6%). Results The mean of follow-up was 29 months (range: 3-92). At the end of the study 69,8% of the patients presented disease stabilization and 23,3% decrease of the tumor size. Only 2,3% of the patients had disease progression. Related to clinical situation, 60,5% of the patients related the same symptom as before the treatment, 9,3% had no symptom and 18,6% had improvement of their quality of live. Only 4,7% of the patients had worsening of their symptoms. No acute toxicity was reported in 65,1% of the patients. The most frequent one was headache and mainly grade 1. In the 79,1% not late toxicity was reported, the remainder presented toxicity grade 1-2 that was easily controlled by medication. Conclusion Fractionated Stereotactic Radiotherapy is a modality of treatment good tolerated and with excellent local control for this kind of meningiomas that have traditionally posed a major challenge for neurosurgeons and neuro- oncologists.