ESTRO 38 Abstract book

S83 ESTRO 38

that sparing of healthy brain tissue should be a crucial aspect in the treatment of brain tumours. Luckily, new techniques are being developed that allow for very precise irradiation of the tumour area, which means cortical sparing is feasible. We here present 2 No Fly zones, to be avoided in cranial radiotherapy. In the future, cognitive symptoms after RT may be diminished further, vastly improving the quality of life of brain tumour patients. OC-0168 Dose-dependent atrophy of the amygdala after radiotherapy M. Huynh-Le 1 , R. Karunamuni 1 , V. Moiseenko 1 , N. Farid 2 , C. McDonald 3 , J. Hattangadi-Gluth 1 , T.M. Seibert 1 1 University of California San Diego, Radiation Medicine and Applied Sciences, San Diego, USA ; 2 University of California San Diego, Radiology, San Diego, USA; 3 University of California San Diego, Psychiatry, San Diego, USA Purpose or Objective The amygdalae are deep brain nuclei critical to processing emotions such as fear, anger, and anxiety, as well as to the creation and storage of memory. The effects of brain radiotherapy (RT) on the amygdalae are currently unknown. We sought to quantify radiation dose-dependent change to the amygdalae in a retrospective cohort of patients with primary brain tumors. Material and Methods 52 patients with primary brain tumors who received fractionated partial brain radiotherapy were identified. Study patients underwent high-resolution, volumetric magnetic resonance imaging before RT and 1 year afterward. Images were processed using software approved by the US Food and Drug Administration and Conformité Européene for automated segmentation of amygdala volume. Results were inspected for accuracy. Tumor and surgical changes were manually censored. Mean dose to the amygdala was tested for correlation with amygdala volume change 1 year after RT via the Pearson correlation coefficient. A linear mixed-effects model was constructed to evaluate potential predictors of amygdala volume change, including patient (random effect), age, tumor hemisphere, sex, seizure history, and bevacizumab treatment during the study period. As 51 of 52 patients (98%) received chemotherapy during the study period, chemotherapy was not included as a predictive variable. A two-tailed p -value of <0.05 was considered to be statistically significant. Results The majority of patients were male (n=35, 67%), and the median age at the time of treatment was 54 years (range 19-77). Most patients had grade III-IV glioma (n=42, 81%). The most common tumor locations were frontal lobe (n=18, 35%) and temporal lobe (n=16, 31%). All patients were treated with intensity-modulated RT. Fifty patients (96%) received chemotherapy concurrent with RT; all of these patients received temozolomide. Fifteen patients (29%) had a major seizure during the study period and ten (19%) patients received bevacizumab. After censoring effects of tumor, surgery, or segmentation error, 40 right and 44 left amygdalae (total of 84 amygdalae) were included in the analyses. Mean dose to the amygdala ( r =- 0.28, p =0.01) was significantly correlated with volume loss. On multivariable analysis, only radiation dose was a significant predictor of amygdala atrophy. The final linear mixed-effects model estimated amygdala volume loss of 0.17% for every 1 Gy increase in mean amygdala RT dose The amygdala demonstrates dose-dependent atrophy at one year after radiotherapy for brain tumors. The potential cognitive effects of radiotherapy to the amygdala warrant further exploration in prospective trials. ( p =0.008). Conclusion

OC-0169 Spinal change after craniospinal irradiation for pediatric patients Y. Oshiro 1 , M. Mizumoto 2 , H. Pan 3 , S. Kaste 4 , T.E. Merchant 1 1 St.Jude Children's Research Hospital-Memphis, Radiation Oncology, Memphis, USA; 2 University of Tsukuba, Radiation Oncology, Tsukuba, Japan; 3 St. Jude Children's Research Hospital- Memphis, Biostatistics, Memphis, USA; 4 St.Jude Children's Research Hospital- Memphis, Diagnostic Imaging, Memphis, USA Purpose or Objective To analyze spinal change after craniospinal irradiation (CSI). Material and Methods 896 vertebral bodies in 220 pediatric patients who received CSI were analyzed. All met the following criteria: age at CSI ≤ 13 years, minimal follow up of 2 years with spinal MRI. CSI dose ranged from 15Gy to 43.2Gy. To analyze vertebral growth, vertebral body height were calculated. Signal change of vertebral body on MRI, scoliosis and kyphosis, degenerative change of vertebral bones and disc, and wedging or vertebral height loss were also analyzed on images. Then impact factors on these changes were investigated. Results Vertebral bone was significantly correlated radiation dose and growth hormone (GH) deficiency. The bone growth rate was 2.6%, 2.0%, 1.6%, 1.8% 1.0%, and 0.8% for bones receiving < 20Gy, 23.4Gy, 36Gy, 39.6Gy, 40-50Gy, and >50Gy, respectively. Growth rate was significantly worse with the dose more than 38Gy. The growth rates were similar for vertebral bodies treated with growth hormone compared to those in whom growth hormone was not indicated (2.73% per year vs. 2.88% per year) whereas in those who refused or unable to receive growth hormone the rate of growth was significantly lower (1.38% per year) compared to those treated with growth hormone (p=0.0022). 83% of the patients showed fatty marrow change and 31% patients had disc degenerative change. Degenerative change of spinal bones and Wedging or spinal height loss was observed in 13% and 17% of the patients. Scoliosis was observed in 27% of the patients. Conclusion Vertebral bone growth was significantly disturbed with the dose >38Gy, and adequate GH replacement was very important for bone growth. Even with symmetrical irradiation, risk of scoliosis was high after CSI, and moreover, spinal demineralization and degenerative change frequently progressed after CSI, therefore, careful attention should be paid for future spinal symptoms as the patients grow old. OC-0170 Proton beam radiation results in Pediatric Head and Neck Rhabdomyosarcoma OC-0171 Hypofractionated SBRT in childhood cancer: preliminary results of a national prospective study L. Claude Defez 1 , S. Bolle 2 , E. Blanc 3 , A. Laprie 4 , A. Huchet 5 , C. Vigneron 6 , A. Escande 7 , M. Morelle 8 , C. Carrie 9 , S. Supiot 10 1 Centre Leon Berard, Radiotherapy, Lyon, France; 2 Gustave Roussy Cancer Campus, Radiation Oncology Department, Villejuif, France; 3 Centre Léon Bérard, Direction de la Recherche Clinique et de l'Innovation, Lyon, France; 4 Institut Universitaire du- Cancer de Toulouse, Radiotherapy, Toulouse, France ; 5 University Hospital of Bordeaux, Radiotherapy, Bordeaux, France; 6 Centre Paul Strauss, Radiotherapy, Strasbourg, France; 7 Oscar Lambret Comprehensive Cancer Center-, Radiation Oncology, Lille, France ; 8 Centre Léon Bérard, Direction de la Recherche Clinique et de l'Innovation- Abstract withdrawn