ESTRO 38 Abstract book

S673 ESTRO 38

II-III.Median OS from the diagnosiswas 37 months (range 12-168) for all patients, 28 months (range 14-80) for GBM and 103 months (range 12-168) for grade II-III. No toxicity during treatment was observed, and all patients completed the CK treatment. No patient developed severe (> grade 3) toxicity. Radiation necrosis was observed in 5 patients (15%). Conclusion Our retrospective experience demonstrates that CK® SRS/SRT retreatment is a feasible and well tolerated option for recurrent Gliomas previous irradiated. In these patients the better treatment choice remains individual and based on a multidisciplinary evaluation. However, a longer follow-up and enrolment of more patients are needed to confirm our results and to guide us in choosing the most appropriate treatment. EP-1218 Upfront stereotactic radiosurgery in patients with brain metastases from small cell lung cancer S. Yomo 1 1 Aizawa Hospital, Division of Radiation Oncology- Aizawa Comprehensive Cancer Center, Matsumoto, Japan Purpose or Objective Because of the high likelihood of multiple brain metastases (BM) from small cell lung cancer (SCLC), the role of focal treatment using stereotactic radiosurgery (SRS) has yet to be determined. We aimed to evaluate the efficacy and limitations of upfront SRS for patients with BM from SCLC. Material and Methods Patients with BM from SCLC who received upfront SRS from 2009 to 2018 without prophylactic or therapeutic whole brain radiotherapy (WBRT) were retrospectively identified from an institutional database.Overall survival (OS), neurological death-free survival, remote and local tumor recurrence rates were analyzed. Results None of 86 consecutive patients were lost to follow-up and the median follow-up for censored observations was 10.3 months. The median age was 69 years, and the median Karnofsky performance status was 90. One- and 2-year OS rates were 37% and 11%, respectively. The median OS time was 8.7 months. One- and 2-year neurological death-free survival rates were 11% and 18%, respectively. In total, 240/301 tumors (80%) in 70 patients (81 %) with radiological follow-up data were evaluated. One- and 2- year rates of remote BM relapse were 57% and 62% (per patient), respectively. One- and 2-year rates of local control failure were 16% and 21% (per lesion), respectively. Repeat SRS, salvage WBRT and microsurgery were subsequently required in 36, 14 and 2 patient, respectively. Symptomatic radiation injury, treated conservatively, developed in 3 patients. Conclusion The present study suggested upfront SRS to be a potentially effective and minimally invasive treatment option for BM from SCLC. Although repeat salvage treatment was needed in nearly half of patients to achieve control of distant BM, such continuation of radiotherapeutic management might contribute to reducing the rate of neurological death. EP-1219 Prognostic factors of salvage stereotactic radiotherapy for recurrent high-grade glioma. K. Takehana 1 , M. Uto 1 , K. Ogura 2 , Y. Arakawa 3 , Y. Mineharu 3 , T. Mizowaki 1 1 Kyoto University Hospital, Department of Radiation Oncology, Kyoto, Japan ; 2 Kobe City Medical Center General Hospital, Department of Therapeutic Radiology, Kobe, Japan ; 3 Kyoto University Hospital, Department of Neurosurgery, Kyoto, Japan

Purpose or Objective Two-session Gamma Knife surgery (GKS) has been recently demonstrated as an effective and less invasive alternative for large metastases (BM) not amenable to microsurgical resection. Taking these results, a clinical question arises as to whether this treatment strategy further improve treatment outcome of symptomatic midsize BM (2-10mL). The aim of the present study was to compare the local therapeutic effects and toxicities of single-session and 2- session GKS in the treatment of symptomatic midsize BM. Material and Methods Patients with focal neurological deficits attributable to midsize BM who underwent upfront GKS from 2011 to 2018 were retrospectively identified from an institutional database. Patients both with post-GKS imaging studies and neurological evaluation on outpatient visit were eligible. The combined endpoint, imaging and/or functional worsening of the lesion treated, was compared between the 2 treatment arms after 1:1 propensity score matching. Results A total of 214 symptomatic midsize BM in 183 cancer patients were identified, including 145 and 69 tumors treated with single-session and 2-session GKS, respectively. After propensity score matching, 63 pairs of tumors were obtained. Gray test showed that two-session GKS achieved a longer local progression-free interval compared with single-session GKS (p = 0.035). Two-session GKS was also associated with greater immediate improvement in KPS scores (18 ± 15 vs 11 ± 13, p = 0.008). Overall survival time in single- and 2-session GKS were 13.4 months and 15.0 months, respectively (p = 0.47). Conclusion Two-session GKS could achieve more durable local tumor control and functional improvement than single-session SRS for patients with symptomatic midsize BM, although overall survival advantage did not become evident. EP-1217 Reirradiation of recurrent gliomas with CyberKnife® SRS/SRT: a monoistitutional experience V. Borzillo 1 , E. Scipilliti 2 , R. Di Franco 1 , F. Cammarota 1 , P. Muto 1 1 Istituto Nazionale Tumori Fondazione Pascale, UOC Radioterapia, Napoli, Italy ; 2 Università Federico II, Dipartimento di scienze biomediche avanzate, Napoli, Italy Purpose or Objective The aim of our study was to retrospectively evaluate the efficacy and toxicity of reirradiation with Cyberknife (CK) stereotactic radiosurgery (SRS)/ stereotactic radiotherapy (SRT) in patients with recurrent gliomas pre-irradiated. Material and Methods Between May 2013 and August 2018, 33 patients (56 lesions) with recurrent gliomas (RGs), previously treated with standard Radiotherapy (RT) (50-60 Gy;1.8-2Gy/fx) with or without concomitant and adjuvant temozolomide (TMZ), were reirradiated with CyberKnife®SRS/SRT.The median time interval between primary RT and reirradiation was 22 months (range 2-116). Twenty patients had a grade IV (GBM), eleven grade III and 2 grade II gliomas. Median Karnofsky performance status was 80 (range 30-100). The total prescription dose of CyberKnife®SRS/SRTretreatment was 20-30 Gy in 5 fractions (fs), 20-26Gy in 4 fs, 15-24 Gy in 3 fs, and 12-24 Gy in single fraction (fx) at isodose line of 80% (range 75- 80%).We calculate median overall survival (OS) from the diagnosis date and median OS from reirradiation. Acute and late toxicities were graded according to Radiation Therapy Oncology Group scale. Results Median follow-up was 8 months (range 0-41). 28/33 patients were evaluable for the FU, because 5 patients died before the first FU. Median OS after SRS/SRT was 8 months (range 0.16-43) for all patients, 6 months (range 0.16-41) for GBM and 15 months (range 0.23-43) for grade