ESTRO 2020 Abstract Book

S653 ESTRO 2020

in 12 Gy group and 1.5 ± 1.0% in 7.5 Gy group, under the acceptable 10% range. 71 (91.0%) patients had abnormal levels of TA values during TBI treatment. The mean ± SD of peak TA values was 368.4 ± 348.2 U/L (n.r. 28-100 U/L). The difference in the maximum TA values between the two TBI groups was not significant ( P = 0,2111). A peak TA value of 374 U/L was identified as the best cut-off possible. TA values > 374 U/L were excellent in predicting the overall survival, with AUC = 0.773 and 95% CI = 0.66 – 0.86 ( P < 0.0001), sensitivity 58.6% and specificity 95.9%. In fact, they were even better in predicting the disease recurrence-related death, with AUC = 0.865 and 95% CI = 0.77 – 0. 93 ( P < 0.0001), sensitivity 80.0% and specificity 88.9%. Kaplan-Meier curve analysis confirmed the statistically higher survival probability in patients with maximum TA values < 374 U/L ( P < 0.0001). Conclusion Human heterogeneity in radiosensitivity has been demonstrated in many studies. In the era of precision medicine, the dosage of total serum total amylase can be an useful tool to precociously identify patients at greater risk of post-TBI complications and worse clinical outcomes. PO-1240 Permanent alopecia after cranial irradiation in childhood cancer survivors. B. Durand 1 , H. Sudour-Bonnange 2 , A.M. Bimbai 3 , S. Raimbault 2 , P. Comte 4 , C. Lervat 2 , A.S. Defachelles 2 , X. Mirabel 1 , E.F. Lartigau 1 , M. Le Deley 3 , A. Escande 1 1 Oscar Lambret Comprehensive Cancer Center, Academic Department of Radiation Oncology, Lille, France ; 2 Oscar Lambret Comprehensive Cancer Center, Department of Paediatric Oncology, Lille, France ; 3 Oscar Lambret Comprehensive Cancer Center, Clinical Research and Clinical Epidemiology Unit, Lille, France ; 4 Oscar Lambret Comprehensive Cancer Center, Department of medical physics, Lille, France Purpose or Objective Intracranial radiation therapy leads to detrimental consequences among cancer survivors, notably in children. To date, no definite criteria have been linked to the occurrence of permanent alopecia after intracranial radiation photon therapy despite its major impact on quality of life. We aimed to determine the incidence and potential factors influencing permanent alopecia occurrence in children treated for a non-hematological solid tumor. Material and Methods We included between February and June 2019, during systematic follow-up visits at the Oscar Lambret Center, Lille, all children who had previously been treated with intracranial radiation therapy more than 3 months before the visit. The dosimetric plan and data were restored and the scalp was contoured in each treatment plan. Permanent alopecia was defined as persistent alopecia at least three months after the completion of the treatment. All dosimetric data and treatments were collected to determine the characteristics associated with permanent alopecia occurrence using univariate analysis. Results Thirty-seven children were consecutively included. They had been treated for medulloblastoma for eight patients (21.6%) and local intracranial tumor for the last ones (29 patients, 78.4%) at an age varying from 1.2 to 21.8 years (median 8.9 years). Among them, 31 (83.8%) had undergone intensity-modulated radiation therapy. Median total dose delivered was 54 Gy. Median scalp maximal dose received in two cubic-centimeters (D2cc) was 38.9 Gy. Twenty-four children (64.9%) had received at least one chemotherapy course during treatment. Overall, 12 patients (32.4%) had persistent alopecia at the time of the visit. According to univariate analysis, only scalp D2cc was significantly associated with permanent alopecia occurrence after intracranial radiation therapy (p=.029). High dose chemotherapy (p=.176) and alopecia induced

chemotherapy (p=.696) were not associated with permanent alopecia. Conclusion Scalp D2cc was the only factor found associated with permanent alopecia after intracranial photon radiation therapy. This constraint should be considered when planning radiotherapy, because of the potential major impact of alopecia on quality of life. PO-1241 Clinical results and toxicities in pediatric CNS tumors treated with proton pencil-beam scanning B. Rombi 1 , A. Ruggi 2 , L. Ronchi 3 , M. Buwenge 3 , I. Ammendolia 3 , S. Cammelli 3 , F. Melchionda 2 , A. Prete 2 , F. Fracchiolla 1 , M. Zucchelli 4 , G. Morganti 3 , M. Amichetti 1 1 Proton Therapy Center - Santa Chiara Hospital, Department of Oncology, Trento, Italy ; 2 University of Bologna- S. Orsola-Malpighi Hospital, Department of Pediatrics, Bologna, Italy ; 3 University of Bologna- S. Orsola-Malpighi Hospital, Radiation Oncology Center - Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy ; 4 Institute of Neurological Science of Bologna IRCCS, Pediatric Neurosurgery Unit, Bologna, Italy Purpose or Objective This monocentric study presents the clinical results and toxicities observed in 16 children with various CNS tumors treated with proton pencil-beam scanning. Material and Methods Between 2015 and 2019, 16 children with CNS tumors received proton therapy (PT), 12/16 with daily anesthesia. Median total dose to the primary tumor site was 54 CGE in 1.8 CGE daily fractions; furthermore, 10 patients received craniospinal irradiation (CSI): seven at 36 CGE, 3 at 23.4 CGE. Tumor histologies were as follows: 8 Medulloblastomas (MB; 3 standard and 5 high risk), 2 Pilocytic Astrocytomas (PA), 3 Atypical Teratoid/Rhabdoid Tumors (AT/RT), 1 pure Germinoma, 1 Choroid Plexus Carcinoma (CPC) and 1 invasive clear-cell Meningioma. All were operated prior to PT: 3 total, 10 partial resections, 3 biopsies. Eleven patients received chemotherapy before PT (5 also received autologous stem-cell transplantation, ASCT), while 5 received chemotherapy after PT. Acute and late toxicities were recorded according to the CTCAE, v4. Results At a median follow-up of 25 months [9 – 47 months], 15/16 patients are alive, 8 show a complete response and 6 a stable disease. Two patients had a disease progression: one patient with a diencephalic AT/RT had a spinal relapse 10 months after PT. Therapy for relapse included chemotherapy with ASCT and craniospinal PT. After 7 months of complete response she relapsed again and finally died to disease progression. The PA patient had a disease progression 10 months after PT (increase of both cystic and solid parts of the residual tumor). Hematological toxicity during PT was mild, no transfusions were necessary. There were no cases of hematological toxicity >G3, with only 4 cases of G3 neutropenia and only in patients who received CSI at 36 CGE (3 of these had received an ASCT before PT). Acute/subacute toxicities (dermatitis, alopecia, fatigue, headache, nausea and vomiting) were mostly mild. The only >G2 cases were: 1 case of G3 PRES, 1 G3 perilesional brain edema in a 13-month-old patient with invasive Meningioma, 1 G3 fatigue and 1 G3 headache. All recovered completely. Four MB patients developed a Herpes virus infection within 1 month from the end of PT. Five out of 16 patients experienced late toxicities: a HR- MB patient had a self-limiting intracranial bleeding (G2) 24 months after PT, in a site that had received 54 CGE; the AT/RT patient who received PT twice developed 15 months after the 1 st PT a Moyamoya arteriopathy, with severe stenoses of intracranial vessels (local dose of 54 CGE). Three patients (1 CPC, 1 HR-MB, 1 AT/RT) developed