ESTRO 2020 Abstract book

S703 ESTRO 2020

plus a 19.8 boost, while the latter 54 CGE on the primitive. A 2-year-old AT/RT patient developed after 15 months an asymptomatic Moyamoya arteriopathy. A 17-year-old patient with HR-MB developed a self-limiting intracranial bleeding (G2) 24 months after PT, in a site that had received 54 CGE. Conclusion We observed limited neuro-radiological toxicities and no radio-necrosis. The result is notable considering the young patient age (6 patients < 4 years old). The incidence of cavernomas seems to be more frequent in patients treated with whole brain irradiation although the number of cases is still limited. A longer follow-up and more patients are needed to better evaluate toxicities after PT. PO-1245 Novel approach in bone metastasis with neuropathic pain: palliative radiotherapy with tapentadol? J. Cacicedo 1 , J.P. Ciria 2 , V. Morillo 3 , L. Martinez_Indart 4 , A. Gomez-Iturriaga 5 , O. Del Hoyo 5 , A. Frias 5 , D. Büchser 5 , I. San Miguel 5 , F. Suarez 6 , A. Gonzalez 6 , F. Casquero 5 1 Cruces University Hospital/Biocruces Health Research Institute, Radiation Oncology, Barakaldo, Spain ; 2 Hospital Universitario Donostia, Radiation Oncology, San Sebastian, Spain ; 3 Hospital Provincial Castellon, Radiation Oncology, Castellon, Spain ; 4 Biocruces Health Research Institute, Biostatistics, Barakaldo, Spain ; 5 Hospital Universitario de Cruces/Biocruces Health Research Institute, Radiation Oncology, Barakaldo, Spain ; 6 Hospital Universitario de Cruces, Radiation Oncology, Barakaldo, Spain Purpose or Objective Neuropathic pain (NP) is a source of distress in patients with bone metastasis (BM) and notoriously resistant to pharmacological intervention. Tapentadol is an opioid with a dual mechanism, expected to be better to treat NP than other opioids, but has no established clinical evidence for cancer related NP. Only one randomized trial explored the role of RT for NP, comparing an 8 Gy single fraction with 20 Gy/5 fractions. There is no study assessing the utility of specific medication targeting neuropathic pain together with palliative RT. The aim of our pilot study was to assess pain response rate (RR) and quality of life (QLF) in patients presenting moderate/severe NP with a novel treatment approach based on tapentadol and 3D-RT. Material and Methods We conducted a prospective multicenter (3 centers) pilot study of patients undergoing palliative RT for painful BM between 2014 and 2017. Patients were assessed before RT using the validated screening DN4 questionnaire (Douleur Neuropathique en 4 questions) to identify NP components. Pain numeric score (0-10) and analgesic intake were recorded and response to RT (8Gy-30Gy/1-10fr) was assessed according to the criteria defined by the International Bone Metastases Consensus. Inclusion criteria: radiological evidence of BM from a known malignancy, NP according to DN4 (cut-off score ≥4), no clinical/radiological evidence of spinal cord compression, worst pain (last 72 hours) numeric score ≥5/10. Endpoints: pain response and QLF assessment with EORTC QLQ-c30 and BM-22 module 1 month and 2 months after the end of RT. The Kruskal-Wallis nonparametric and Wilcoxon rank sum tests compared changes in QOL among response groups Results Poster: Clinical track: Palliation

Seventeen patients (13 men, 4 woman) with a median age 67 years (42-81) were included (see Table 1). Pre- treatment median index pain severity was 7 (5-10). The median dose of tapentadol administered before RT was 100mg/24h (100-300mg). Four patients stopped tapentadol during the study (1 due to constipation GIII, 1 due to dizziness GII, 1 diarrhea GII, 1 unknown). Sixteen patients were assessable 1 month after RT and ten at 2 months. The overall RR 1 month after RT was 10/16=62.6%; 18.8% achieving a complete response (CR) and 43.8% a partial response (PR). The overall RR 2 months after RT was 5/10=50%; 10% achieving a CR and 40% a PR. In overall, for EORTC QLQ-c30, the median global health basal scores at baseline, 1 month and 2 months after RT were: 33.33, 50 (p=0.013) and 75 (p=0.011), respectively. Patients who responded to RT had significant improvement in EORTC QLQ-c30 emotional functioning (EF) (p=0.025) and fatigue symptom scale scores (p=0.035) one month after RT. There was also a statistically significant improvement (p=0.024) in painful site symptom QLQ-BM22 scores between baseline and 2 months after RT (Figure 1). Conclusion Palliative RT plus tapentadol shows remarkable pain response and QLF improvement especially regarding EF, fatigue and painful site symptom scales in patients with BM and moderate/severe NP. PO-1246 Stereotactic Body Radiotherapy For Bone Metastases In Oligometastatic-Oligoprogressive Patients F. Zerbetto 1 , C.L. Deantoni 1 , F. Borroni 1 , R. Tummineri 1 , A. Fodor 1 , M. Pasetti 1 , A. Chiara 1 , S. Broggi 2 , B. Longobardi 2 , L. Perna 2 , C. Fiorino 2 , N.G. Di Muzio 1,3