ESTRO 2020 Abstract Book

S191 ESTRO 2020

Carlo Besta, Department of Neurosurgery- Radiotherapy Unit, Milan, Italy ; 3 Fondazione IRCCS Istituto neurologico Carlo Besta, Clinic Neuro-Oncology Unit, Milan, Italy Purpose or Objective Patients with sporadic VS treated with a single dose of SRS with a minimum follow-up > 3years were retrospectively analysed to asses tumor control (TC) and SRS related toxicity. Material and Methods Patients received Linac-based (LB) SRS or Cyber-Knife (CK) SRS. Patients not able to discriminate words or not hearing at all, were scored as ‘non-serviceable hearing’. Trigeminal and facial nerve functions were assessed before and after treatment. Results Between 2002 and 2016, 153 VS were treated in 153 patients. 116(76%) VS received LB-SRS and 37(24%) CK-SRS. Male/female ratio was 70/83. Median age was 60y (range,20-84). Median prescribed dose was 14Gy (range, 12-20). Median tumor diameter was 5mm (range,0.2-23). SRS was performed as salvage therapy for recurrent or progressive tumors in 36(23%) patients already submitted to total or subtotal resection (10-28% and 26-72%, respectively). The other 117(77%) patients underwent SRS alone. 25(16%), 61(40%), 52(34%) and 15(10%) VS were classified as Koos tumor grade I, II, III and IV, respectively. 147(96%) patients had hearing loss as an initial symptom, of which 73 (48%) with “non-serviceable” hearing function. Trigeminal neuralgia and facial pain/paraesthesia were presenting symptoms in 9(6%) and 27(17%) patients, respectively. At a median follow-up of 6 years(range,3– 16), 32(21%)patients had an objective improvement of their initial symptoms, 94(61%) stable symptoms, and 27(18%) worsened their pre-treatment symptoms. Only in 2(1%) cases MRI showed progression of VS. Crude radiologic TC rate was 99%. TC was not conditioned by tumour volume, prescribed dose (≤14Gy vs >14Gy), Koos tumor class (I+II vs III+IV) and/or previous surgery. Among patients with “serviceable-hearing” (80-52%), 54(67%) maintained their functional hearing score, 15(19%) improved and 11(14%) worsened. Median tumor size in “serviceable-hearing” patients was 5mm (range, 0,2-30) and median dose administered was 14Gy (range, 12-17,5). No statistically significant difference was found with regard to tumor size (≤5mm vs>5mm) and prescribed dose (≥14 Gy vs<14 Gy).5 of 126(4%) patients without pre-SRS facial toxicity, developed incomplete facial nerve palsy, that regressed in a median time of 6 months. 15 of 144(10%) patients without pre-SRS trigeminal neuralgia developed trigeminal toxicity which was transient or stable/mild during follow-up in 13 (8.5%) patients. In only 2(1%) cases trigeminal toxicity was severe and appeared at a median time of 12 months. Late toxicity was significantly correlated to tumor size (≤5mm vs >5mm) (p=0.05). Prescribed dose and Koos tumor grade (I+II vs III+IV) not showed a statistically significant. Conclusion Our data confirm the feasibility of SRS in the treatment of VS also in patients with “serviceable hearing” with a high rate of hearing preservation. The present analysis of VS patients with a median FU of ≥ 6 years confirmed the excellent TC and low iatrogenic toxicity of both LB-SRS and CK-SRS.

D. Amelio 1 , D. Scartoni 1 , S. Vennarini 1 , A. Turkaj 1 , I. Giacomelli 1 , M. Amichetti 1 1 Centro di Protonterapia, U.O. Protonterapia- Azienda Provinciale per i Servizi Sanitari - Trento, Trento, Italy Purpose or Objective Despite the favorable outcomes with local control rates of up to 90% after ten years, progression after radiotherapy (RT) of intracranial meningiomas (MS) does occur. In those cases, re-irradiation is often difficult due to the limited radiation tolerance of the surrounding tissue. Aim of this analysis is to report safety and efficacy of proton therapy (PT) for re-irradiation of recurrent MS Material and Methods Between March 2015 and June 2019, 25 patients (pts) with 29 intracranial MS were re-irradiated with PT at our institution. Location of the primary lesion was skull base (n = 21) and convexity (n = 8). All but two pts had histologically proven diagnosis of MS (80% were WHO grade II). Median age was 66 years (range, 38-83). Median Karnofsky Performance status was 80 (range, 70-100). All pts failed after previous RT: 33% after Gamma-knife, 43% after Cyber-Knife, 10% after Tomotherapy, 14% after Linac-based stereotactic radiotherapy. Median time from initial irradiation to re-irradiation was 36 months (range, 18-60). Treatment planning was based on morphological magnetic resonance imaging (MRI) with contrast enhancement medium administration. All pts received also 68-Ga-DOTATOC-PET to identify the so-called Biological Tumor Volume. Clinical target volume ranged from 7 to 176 cc. All but one pts (who received 60 Gy in 30 fractions) were treated with 54 GyRBE in 30 fractions. All the pts was treated with active beam scanning PT using 3-4 fields with single or multiple field optimization technique. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.0. Median follow-up time was 12 months (range, 3-51) Results All the pts completed the treatment without breaks. Registered acute side effects include grade 1 (14%) headache, grade 1 (10%) conjunctivitis, grade 2 (38%) skin erythema, grade 1 (14%) and grade 2 (24%) alopecia, grade 2 (10%) pain, grade 2 (10%) otitis, grade 2 (5%) dizziness, grade 2 (5%) tinnitus. There was no grade 3 or higher acute toxicities. Registered late side effects include grade 1 (5%) and grade 2 (5%) alopecia, grade 1 (10%) skin hyperpigmentation, and grade 1 (5%) headache. There was no grade 3 or higher late toxicities. During follow-up two pts (7%) developed radionecrosis (diagnosed at imaging) with no symptoms and no need of steroids. Another pts (5%) developed hydrocephalus that needed ventriculoperitoneal drain. Currently, absolute treated site tumor control is 80%, while absolute tumor control is 76%. Median time to local or distant tumor progression was 13 months. Disease specific absolute survival after re- irradiation is 95%, while absolute overall survival is 81%: three pts died of other causes than MS after re-irradiation. Moreover, relief of symptoms recorded before irradiation occurred in 35% of pts Conclusion Reirradiation with PT of MS progressing after previous RT appears to be feasible with promising clinical outcomes and an acceptable toxicity profile. Longer follow-up is necessary to assess definitive efficacy PH-0358 A score to predict survival of elderly patients newly diagnosed for Glioblastoma C. Straube 1 , K.A. Kessel 1 , S. Antoni 1 , J. Gempt 2 , B. Meyer 2 , J. Schlegel 3 , F. Schmidt-Graf 4 , S.E. Combs 1

PH-0357 Proton therapy re-irradiation of intracranial meningiomas failing after previous radiation therapy.