Abstract Book

S307

ESTRO 37

and disclose important novel interactions between Notch inhibition and radiotherapy.

Proffered Papers: CL 11: CNS

OC-0587 Hypofractionated radiotherapy vs temozolomide in glioblastoma RPA V-VI: a randomized phase II trial S. Pedretti 1 , L. Masini 2 , E. Turco 3 , L. Triggiani 1 , M.Krengli 2 , B. Meduri 3 , L. Pirtoli 4 , M. Faedi 5 , R. Gatta 1 , S. Scoccianti 6 , U. Ricardi 7 , R. Santoni 8 , S. Magrini 1 , M. Buglione 1 1 Spedali Civili di Brescia and Brescia University, Radiation Oncology, Brescia, Italy 2 AOU Maggiore della Carità, Radiation Oncology, Novara, Italy 3 AOU Modena, Radiiation Oncology, Modena, Italy 4 AOU Senese, Radiation Oncology, Siena, Italy 5 IRST IRCCS, Radiation Oncology, Meldola, Italy 6 AOU Careggi, Radiation Oncology, Firenze, Italy 7 University of Turin, Radiation Oncology, Torino, Italy 8 University of Rome - Tor Vergata, Radiation Oncology, Rome, Italy Purpose or Objective to compare hypofractionated radiotherapy and temozolomide chemotherapy in terms of survival and quality of life in patients affected by poor prognosis glioblastoma. Material and Methods patients (pts) with histologic diagnosis of glioblastoma (RPA V-VI) were randomized to hypofractionated radiotherapy (RT -30 Gy in 6 fractions on alternate days) and exclusive chemotherapy (CHT - temozolomide 5 days/28 days - 200mg/m 2 /day). Overall (OS) and progression free survival (PFS) were evaluated with Kaplan Maier curves and correlated with prognostic factors with log-rank test. Quality-adjusted survival (QAS) was evaluated according to the Murray model with the NNS scheme (Int J Radiat Oncol Biol Phys. 1995 Feb 1;31(3):453-9.) Results From 2010 to 2015, 31 pts were enrolled in 6 Radiotherapy Centers: 17 pts in the CHT group and 14 pts in the RT one. Four pts were excluded from analysis: 2 pts withdrew informed consent and 2 had clinical deterioration before the beginning of treatment and had supportive therapy only. Median age was 69 years (55-82 years). Two pts had IMRT with daily IGRT, the others had 3D conformal radiotherapy. CHT was interrupted after an average of 2 cycles (range 1-6) for clinical deterioration and disease progression. Median OS and PFS was 7,6 and 3,8 months respectively. Age> 70 years (p=0,048) and RPA VI (p=0,03) worsened OS significantly. Biopsy instead of extended surgery (p=0,038), RPA class VI (p=0,001) and chemotherapy (p=0,007 – Figure 1a) are related to a worse PFS. In the RTT arm, mild headache (grade I) was recorded in 90% of pts; in the CHT one, 3/17 pts had to reduce the dose of chemotherapy for grade I-II thrombocytopenia. In the two arms the initial NNS score was overlapping: 12.23 in CHT group and 12.3 in RT group. Figure 2 shows how NNS score progressively decreased in both groups but became significantly worse after 6 months in CHT group (p = 0.005- Anova test). Median QAS was 3,4 months (range 1-15,4 months); QAS was significantly better in RTT group (p=0,001 – Figure 1b).

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2

Conclusion The data obtained from this multicentre randomized phase II clinical trial are limited by the poor accrual. Both treatments were well tolerated by patients without evidence of severe toxicities. Patients treated with hypofractionated radiotherapy have a better PFS and QAS, compared to patients in the CHT group, without incident on OS. In our case the deterioration of the NNS score would seem caused by disease progression rather than by the toxicity of the treatment. On behalf of Brain Study Group of the Italian Association of Radiation Oncology (AIRO). OC-0588 Validation of the reRT risk score (RRRS) in glioma patients: A multicenter DKTK/ROG analysis M. Niyazi 1 , S. Adeberg 2 , D. Kaul 3 , A.L. Boulesteix 4 , N. Bougatf 2 , D.F. Fleischmann 1 , A. Grün 3 , A. Krämer 5 , C. Rödel 5 , F. Eckert 6 , F. Paulsen 6 , K.A. Kessel 7 , S.E. Combs 7 , O. Oehlke 8 , A.L. Grosu 8 , A. Seidlitz 9 , A. Lattermann 9 , M. Krause 9 , M. Baumann 10 , M. Guberina 11 , M. Stuschke 11 , V. Budach 3 , C. Belka 1 , J. Debus 2 1 LMU Munich, Dep. of Radiation Oncology, Munich, Germany 2 University of Heidelberg, Dep. of Radiation Oncology, Heidelberg, Germany 3 Charité-University Hospital Berlin, Dep. of Radiation Oncology, Berlin, Germany 4 Biometry and Epidemiology- University of Munich, Department of Medical Informatics, Munich, Germany 5 University Hospital Johann Wolfgang Goethe University, Dep. of Radiation Oncology, Frankfurt, Germany 6 Faculty of Medicine and University Hospital Tübingen, Dep. of Radiation Oncology, Tübingen, Germany 7 Klinikum rechts der Isar- Technische Universität München, Dep. of Radiation Oncology, Munich, Germany 8 University Medical Center Freiburg, Dep. of Radiation Oncology, Freiburg, Germany 9 Faculty of Medicine and University Hospital Carl Gustav Carus- Technische Universität Dresden, Dep. of Radiotherapy and Radiation Oncology, Dresden, Germany 10 German Cancer Research Center DKFZ, German Cancer Consortium DKTK, Heidelberg, Germany 11 University of Duisburg-Essen- University Hospital Essen, Dep. of Radiotherapy, Essen, Germany Purpose or Objective Reirradiation (reRT) is an option with considerable efficacy in patients with recurrent high-grade glioma. However, conclusive evidence regarding its use is lacking. Therefore, it is still not known which patients might be