Abstract Book

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ESTRO 37

Material and Methods In this multi-cohort non-randomized phase-II (WHO grade II) and observational study (WHO grade III), non-benign meningioma patients were treated according to their WHO grade and Simpson’s grade. For patients with atypical meningioma (grade II) and Simpson’s grade 1-3, [Arm 1] the trial was designed as a non-randomized phase-II with PFS-3Y as primary endpoint. For Arm 1, the study would be considered as a success if the 1-sided confidence interval (CI) around the PFS-3Y estimated from the Kaplan-Meier curve would be superior to 70%. Using a 1-sided type I error of 2.5% and a power of 95%, 54 eligible patients who received RT were needed. No specific statistical design was planned for the 3 other cohorts (Grade II, Simpson grade 4-5 [Arm 2] and Grade III, Simpson grade 1-3 or 4-5 [Arm 3&4]) due to small foreseen numbers of patients recruited. Results Between 02/2008 and 06/2013, 78 patients were enrolled in the trial. The results below focuses only on the 56 eligible patients (female: n =27; 48%) with WHO grade II Simpson’s grade 1-3 meningioma. Median age was 54 years (range, 28-72). WHO performance status was 0, 1 and 2 in 75%, 14%, 11% of patients, respectively. Median duration of RT was 44 days. At a median follow up of 5.1 years, the estimated PFS-3Y is 88.7% (95% CI: 76.5, 94.8). One patient had distant metastasis, all other recurring patients ( n =7) presented local progressions. The majority (75%) of patients were salvaged by additional RT ( n =3), RT and surgery ( n =2) and surgery alone ( n =1). One patient died due to cardiovascular disease, two as a result of meningioma. The estimated 3-year overall survival (OS-3Y) was 98.2% (95% CI = 87.6, 99.7). Ten serious acute and late adverse events were observed in 8 (14%) patients (grade II, n=1; grade III, n =6; grade IV, n =3). No toxic death was observed. Conclusion These data stemming from a prospective phase II study successfully showed that PFS-3Y for WHO grade II meningioma patients undergoing a complete resection (Simpson I-III) is superior to 70% when treated with high- dose (60 Gy) RT. The estimated OS-3Y was excellent. Fourteen percent of patients presented with grade 3-4 serious adverse events after RT. OC-0590 Screening MRI for radiation-induced meningioma in childhood cancer survivors with prior cranial RT J. Co 1 , M. Swain 1 , L. Murray 1 , S. Ahmed 1 , N. Laperriere 1 , D. Tsang 1 , D. Hodgson 1 1 Princess Margaret Cancer Centre, Radiation Oncology, Toronto, Canada Purpose or Objective Radiation-induced meningioma (RIM) is a known late effect of cranial radiotherapy. Cranial MRI screening in a high risk population may detect these meningiomas early but currently its value is not well defined. This study describes the outcome of MRI screening among survivors of childhood leukemia who were treated with cranial RT (CRT). Material and Methods The study cohort at risk for RIM was composed of childhood leukemia survivors who received CRT and attended the pediatric aftercare clinic in our cancer centre from January 2005 to February 2017. MRI screening for RIM was implemented in January 1, 2013. The screened group was composed of those who had screening cranial MRI from January 1, 2013 to February 2017. Outcomes of this group were compared with those attending clinic who underwent cranial MRI only for symptomatic presentation, before the implementation of routine screening. We also compared the outcome of RIM with outcomes of 150 randomly selected adult cases of sporadic meningioma seen at our centre.

optimal candidates for a second course of irradiation. This study validated a newly developed prognostic score independently in an external patient cohort. Material and Methods The reRT risk score (RRRS) is based on a linear combination of initial histology, clinical performance status (both dichotomized), and age (continuous) and derived from a multivariable model of 353 patients. This score can predict post-recurrence survival (PRS) after reRT. The validation dataset consisted of 212 patients. An online tool was developed to provide the respective risk category. Results The RRRS differentiates three prognostic groups. Discrimination and calibration were maintained in the validation group. Median PRS times in the development cohort for the good/intermediate/poor risk categories were 14.2, 9.1, and 5.3 months, respectively. The respective groups within the validation cohort displayed median PRS times of 13.8, 8.8, and 3.8 months, respectively. Hazard ratios with the intermediate risk group as reference were comparable in both cohorts. Harrell’s/Uno’s C for development data were 0.648/0.646 and for the validation data 0.633/0.628. Conclusion The RRRS has been successfully validated in an independent patient cohort. This linear combination of three easily determined clinicopathological factors allows for a reliable classification of patients and may be used as stratification factor for future clinical trials. Moreover, it can be utilized for the proper selection of candidates for reRT. OC-0589 Phase-II parallel non-randomized/observation study (EORTC 22042-26042) for non-benign meningiomas D.C. Weber 1 , C. Ares 2 , S. Villa 3 , S.M. Peerdeman 4 , L. Renard 5 , B.G. Baumert 6 , A. Lucas 7 , J.J. Stelmes 8 , S. Collette 9 , R. Miralbell 10 1 Paul Scherrer Institute PSI, Radiation Oncology, Villigen PSI, Switzerland 2 Geneva University Hospital, Radiation Oncology, Geneva, Switzerland 3 Hospital Germans Trias i Pujol, Radiation Oncology, Barcelona, Spain 4 VU University Medical Center- Amsterdam, Department of Neurosurgery, Amsterdam, The Netherlands 5 Cliniques universitaires St Luc, Service de Radiothérapie oncologique, Brussels, Belgium 6 Maastricht University Medical Centre, Dept. Radiation- Oncology MAASTRO Clinic- & GROW School for Oncology-, Maastricht, The Netherlands 7 Institut Català d'Oncologia - L'Hospitalet, Department of Radiation Oncology, Barcelona, Spain 8 EORTC HQ, RTQA group, Brussels, Belgium 9 EORTC HQ, Department of Statistics, Brussels, Belgium 10 Geneva University Hospital, Department of Radiation Oncology, Geneva, Switzerland Purpose or Objective The therapeutic strategy for non-benign meningiomas is controversial. Some retrospective studies have shown that administrating higher dose of radiation could optimize meningioma patient’s outcome for grade WHO II and III tumors alike. The objective of this phase II trial in meningioma was to prospectively investigate the impact of high dose radiation therapy (RT) on the progression- free survival rate at 3-years (PFS-3Y). The hypothesis is that high dose (60Gy and 70Gy for Simpson grade 1-3 and 4-5, respectively) radiation therapy (RT) would increase the PFS-3Y in patients with meningioma WHO grade II. For WHO grade III tumors, the patients were registered only, treated and were followed-up similarly to the grade II meningiomas.