Presenter(s)
M. L. Rose1, K. W. Allison1, G. S. Gill2, B. Bajaj1, S. L. Dennehy1, L. Wiltsie3, K. Litzinger1, A. Perry1, A. Armstrong-Javors4, W. Butler5, H. Elhalawani1, K. X. Liu6, D. A. Haas-Kogan6, and T. I. Yock6; 1Department of Radiation Oncology, Mass General Brigham, Harvard Medical School, Boston, MA, 2Department of Radiation Oncology, The University of Alabama at Birmingham School of Medicine, Birmingham, AL, 3Department of Pediatric Hematology & Oncology, Massachusetts General Brigham, Harvard Medical School, Boston, MA, 4Department of Pediatric Neurology, Massachusetts General Brigham, Harvard Medical School, Boston, MA, 5Department of Neurosurgery, Mass General Brigham Cancer Institute, Boston, MA, 6Department of Radiation Oncology, Mass General Brigham, Boston, MA
Purpose/Objective(s): Pediatric ependymomas are common brain tumors in children, with a high rate of long-term disease control with maximal safe resection and adjuvant radiotherapy. For patients who recur, the data regarding re-irradiation remains limited. We explore the safety and efficacy of proton therapy in the reirradiation setting.
Materials/Methods: IRB approval was obtained to search our pediatric database for patients (<23 years at diagnosis) with history of ependymoma and multiple courses of radiotherapy. Patients were included if they had received proton therapy as their second course of RT in the setting of disease recurrence. Local control (LC) was calculated using the cumulative incidence method, and progression free survival (PFS) and overall survival (OS) were calculated using the Kaplan-Meier method from start of second course of radiation. Treatment related toxicity was graded according to CTCAE version 6.0. Statistical analyses were performed using R.
Results: 41 patients were included with a total of 126 courses of re-irradiation. Initial courses of radiotherapy took place between 2002-2022. Median follow-up after the 2nd radiation was 6.9 years. Median time to first failure was 28.0 months. Median age at time of re-irradiation was 8.5 years. The majority of patient had infratentorial tumors (n=30, 73%), anaplastic histology (n=34, 83%), and local recurrence as first site of disease failure (n=28, 68%). Median dose of RT at reirradiation was 52.5 GyRBE (range 30.0-60.0). All patients received focal radiotherapy at the time of first recurrence. Three-year LC was 57.6%, PFS 40.2%, and OS 74.6%. 58% of patients reported no long-term toxicity, one patient had a grade 3 toxicity, and no patients reported grade 4+ toxicities.
Conclusion: Proton therapy remains a safe and effective option for re-irradiation in the treatment of recurrent ependymoma. With longer-term follow-up, proton re-irradiation continues to demonstrate durable control and serves as an effective salvage strategy for patients with recurrent disease for patients with local and/or distant recurrence.