2387 - The Results of Re-Irradiation in Pediatric Recurrent Central Nervous System Tumors
Presenter(s)
A. Iribas1, K. Özkaya Toraman2, M. U. Abacioglu3, E. K. Tezcanli4, Z. Güral5, Y. Dizdar6, Ü. M. Yildirim7, R. Kebudi8, C. Ilgin9, B. Sahin Baris10, and F. Agaoglu5; 1Istanbul University, Faculty of Medicine, Department of Radiation Oncology, Istanbul, Turkey, Istanbul, Turkey, 2Istanbul University, Institute of Oncology, Radiation Oncology Department, Istanbul, Turkey, 3Department of Radiation Oncology Acibadem University, School of Medicine. Acibadem Altunizade & Atasehir Hospitals, Istanbul, Turkey, 4Acibadem University, Istanbul, Turkey, 5Acibadem Mehmet Ali Aydinlar University Atakent Hospital, Istanbul, Turkey, 6Istanbul University, Faculty of Medicine, Department of Radiation Oncology, Istanbul, Turkey, istanbul, Turkey, 7Istanbul University, Oncology Institute, Division of Pediatric Hematology Oncology, Istanbul, Turkey, Istanbul, Turkey, 8Istanbul University, Oncology Institute, Division of Pediatric Hematology Oncology, Istanbul, Turkey, istanbul, Turkey, 9Istanbul University Istanbul Medical Faculty Radiation Oncology Department, Istanbul, Turkey, 10Acibadem Mehmet Ali Aydinlar University, Faculty of Medicine, Department of Radiation Oncology, Istanbul, Turkey
Purpose/Objective(s): The use of re-irradiation in recurrent pediatric central nervous system (CNS) tumors has increased over the past decade due to advancements in radiotherapy techniques. This study aims to analyze factors influencing overall survival (OS) and progression-free survival (PFS) in pediatric patients with recurrent CNS tumors who underwent re-irradiation.
Materials/Methods: A total of 81 pediatric patients diagnosed with CNS tumors and treated with re-irradiation for recurrence between 1990 and 2023 were included in this retrospective study.
Results: The median follow-up duration was 45 months (7–325). The median age at diagnosis was 7 years (0–17), and 75.31% of patients were male. The most common tumor type was medulloblastoma (46.91%), followed by ependymoma (24.69%) and diffuse intrinsic pontine glioma (DIPG)/diffuse midline glioma (DMG) (18.52%). Gross total resection (GTR) was performed in 63.16% of cases, subtotal resection in 28.95%, and biopsy alone in 7.89%. Cerebrospinal fluid (CSF) dissemination was detected in 19.75% of patients, while spinal axis involvement was observed in 25.93% on magnetic resonance imaging (MRI).
The median time from initial diagnosis to recurrence was 20 months (3–132). At recurrence, CSF dissemination and spinal axis involvement on MRI were detected in 17.28% and 43.21% of patients, respectively. More than half of the patients (51.32%) had neurological deficits at recurrence. Surgical intervention at recurrence was performed in 40.74% of cases. Most patients received either craniospinal (47.5%) or cranial (46.25%) re-irradiation, with only 6.25% receiving spinal irradiation at recurrence time. Among recurrent medulloblastoma cases, 64.86% received craniospinal and 24.32% received cranial re-irradiation. All recurrent ependymoma patients underwent either craniospinal (50%) or cranial (50%) radiotherapy. The majority of recurrent DIPG/DMG patients (86.67%) received cranial re-irradiation. The 2-year and 5-year OS rates were 72.68% and 43.55%, respectively, while the 2-year and 5-year PFS rates were 48.06% and 24.13%, respectively. According to univariate Cox regression analysis, a time to recurrence of <24 months (HR=5.994, 95% CI 3.256–11.032, p<0.001), subtotal resection (HR=1.826, 95% CI 1.024–3.256, p=0.041) or biopsy (HR=5.413, 95% CI 1.978–14.808, p=0.001) instead of GTR, and DIPG/DMG diagnosis (HR=2.798, 95% CI 1.471–5.323, p=0.002) were significantly associated with worse OS. DIPG/DMG diagnosis (HR=2.093, 95% CI 1.139–3.848, p=0.017) and neurological deficits at recurrence (HR=1.813, 95% CI 1.041–3.157, p=0.036) were significantly associated with shorter PFS.Conclusion: A recurrence interval of <24 months, absence of GTR, and DIPG/DMG diagnosis were significant negative prognostic factors for OS in pediatric CNS tumors. Additionally, DIPG/DMG diagnosis and neurological deficits at recurrence were significantly associated with reduced PFS.