S357
Clinical - CNS
ESTRO 2026
Intermediate Differentiation (PPTID): A Retrospective Study Ammar H Salkini 1,2 , Ajay T Alex 2,3 , Dana M Keilty 2,3 , Barbara-Ann Millar 2,3 , Derek S Tsang 2,3 1 MD Program, Temerty Faculty of Medicine, University of Toronto, Toronto, Canada. 2 Department of Radiation Oncology, Princess Margaret Cancer Center, Toronto, Canada. 3 Radiation Medicine Program, Princess Margaret Cancer Center, Toronto, Canada Purpose/Objective: There is limited data evaluating the outcomes of adjuvant RT regimens in PPTID. Practice varies from focal RT alone to cranio-spinal irradiation (CSI), with multiple dose prescriptions reported in the literature.1,2 In this retrospective cohort, we compare outcomes of different RT dose regimens in grade 2 and 3 tumors. Material/Methods: We included all patients with histologically-confirmed PPTID treated with RT at our centre between 2007 and 2025. Curative-intent therapy comprised surgery followed by focal RT or CSI with boost. Tumours were graded as 2 (n=6) or 3 (n=6) and classified as localized (n=10) or metastatic (n=2) at the time of RT. Focal fractionated RT doses included 54 or 59.4 Gy, or 15 Gy radiosurgery (SRS); CSI prescriptions included 23.4 (n=3) or 36 Gy (n=2). Overall (OS) and progression-free survival (PFS) were calculated using the Kaplan-Meier
PPTID. Upfront (not deferred) focal RT showed excellent outcomes in localized Grade 2 tumors. CSI showed favorable outcomes in metastatic Grade 2 and localized grade 3 tumors. Future prospective studies should validate use of reduced-dose CSI (23.4 Gy) in localized Grade 3 PPTID to maintain disease control while minimising treatment toxicity.
References: Liu, A.P.Y., Li B.K., Vasiljevic A., Dewan
M.C., Tamrazi B.,et al. SNO-EANO-EURACAN consensus on management of pineal parenchymal tumors. Neuro Oncology26, 2159–2173 (2024). https://doi.org/10.1093/neuonc/noae128Depan i, S., Vasiljevic, A., Mynarek, M., Dufour, C., Pfaff, E., et al (on behalf of the SIOP-Europe Rare Embryonal and Sarcomatous Tumours (REST) group). European clinical practice recommendations for the diagnosis and treatment of paediatric pineal tumours. EJC Paediatric Oncology5 , 100217 (2025). https://doi.org/10.1016/j.ejcped.2025.100217 Keywords: Pineal tumors, Craniospinal irradiation (CSI) Dose escalation with intraoperative radiotherapy in newly-diagnosed glioblastoma (INTRAGO-II): an open-label, multicentre, randomised phase 3 trial Frank A. Giordano 1,2 , Oliver Ganslandt 3 , Marc Muenter 4 , Stephanie E. Combs 5 , Christian Diehl 5 , Bernhard Meyer 6 , Ulrich Herrlinger 7 , Matthias Schneider 8 , Klaus-Henning Kahl 9 , Ehab Shiban 10 , Anuj Goenka 11 , Michael Schulder 12 , Anna Lucas 13 , Gerard Plans 14 , Stefanie Brehmer 15 , Arne M. Ruder 1 , Sonia Garcia 16 , Juan Solivera 17 , Christopher P. Cifarelli 18 , Frederik Wenz 19 , Julian P. Layer 20,21 , Gustavo R. Sarria 20 , Whitney B. Pope 22 , Christina I. Tsien 23 , Kevin Petrecca 24 Proffered Paper 759
method. Results:
Twelve patients were identified (M:F = 1:1), with a median age of 26.5 years (range 15–71) and median follow-up of 92.5 months. At the time of RT, 10 patients (83%) had localized disease, and two (17%) had metastatic disease. The 5-year OS and PFS estimates were 100% (95% CI 77.9–100%) and 91.7% (95% CI 53.7–98.8%), respectively. Six patients (50%) were classified as grade 2. Localized grade 2 tumors (n=4) received focal RT (54Gy, 59.4Gy, 15Gy SRS; n=3) or gross total resection with no RT (n=1); no recurrences were observed. Metastatic grade 2 tumors (n=2) received upfront (n=1) or salvage (n=1) CSI 36 Gy; the patient who received salvage CSI after their second recurrence later died. All grade 3 tumors (n=6) were localized at RT. Five patients received CSI (23.4 Gy, n=3; 36 Gy, n=2) with no recurrences. One patient received focal RT (59.4 Gy) and developed spinal recurrence; no further progression was observed at last follow- up. Treatment-related toxicities included radiation necrosis (grade 3 in one patient who received focal RT 59.4 Gy), retinopathy (grade 3; CSI 36 Gy), hearing impairment (grade 2; CSI 36 Gy), and cognitive disturbance (grade 1 in two patients; CSI 36 Gy and 15Gy SRS). Conclusion: Our results support a risk-adapted RT approach for
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