2000 - Reirradiation for Primary Central Nervous System Tumors: A Retrospective Single- Institutional Review
Presenter(s)
A. A. Abbasi1, J. Wei1, L. C. Linkowski1, J. Y. K. Lee2, N. Amankulor3, D. O'Rourke2, R. A. Lustig1, J. F. Dorsey1, G. Kurtz4, H. G. Hubbeling4, E. S. Lebow1, and M. Alonso-Basanta1; 1Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 2Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 3Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA, 4Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA
Purpose/Objective(s): Primary central nervous system (CNS) tumors pose a therapeutic challenge due to high recurrence rates despite advances in radiation techniques. The primary goal of this retrospective study is to report reirradiation outcomes in primary CNS tumors at our institution. We hypothesize that reirradiation can be delivered safely in select CNS tumor patients with acceptable outcomes and toxicities. To our knowledge, this is the first series reporting reirradiation outcomes across photon therapy, proton therapy, and stereotactic radiosurgery (SRS) for multiple CNS tumor histologies.
Materials/Methods: We conducted a retrospective review of patients with primary CNS tumors treated with reirradiation at our institution from 2010 to 2021. Treatment modalities included photon therapy, proton therapy, and SRS. Data on patient demographics, tumor characteristics, treatment details, and outcomes was collected and analyzed using descriptive statistics. The primary outcome was overall survival since reirradiation. Secondary outcomes included acute and late (=3 months) toxicities. Toxicities were assessed according to CTCAE v5.0 grading criteria. Radiation necrosis was defined as being symptomatic or requiring intervention.
Results: Among 135 patients (53 female, 82 male), median age at diagnosis was 45 years (range 11-76), with a median age at reirradiation of 46 years (range 14-78). Glioblastoma was the most common diagnosis (61%), followed by meningioma (14%) and various other types of gliomas. The median interval between initial radiation and reirradiation was 1.6 years (range 0.1-35.1). For reirradiation, proton therapy was most frequently used (n=54, 40%), followed by photon therapy (n=44, 33%), and then SRS (n=37, 27%). The median reirradiation dose was 35 Gy (range 9-60). Median follow-up was 2.6 years (range 0.9-23.8). Acute and late toxicities post reirradiation were predominantly grade 1-2 and within acceptable limits. Radiation necrosis occurred in 5% (2/44) of patients in the photon cohort, 19% (10/54) of patients in the proton cohort, and 22% (8/37) of patients in the SRS cohort. Both cases of radiation necrosis in the photon cohort were seen with glioblastomas. In the proton cohort, 7 of the radiation necrosis cases were in patients with gliomas, 2 with meningiomas, and 1 with schwannoma; in the SRS cohort, 7 were with gliomas and 1 with meningioma. Median overall survival was 9.5 months (range 0.8-144.2) for the entire cohort, 8.1 months (range 1.0-27.7) for patients with glioblastomas, and 28.9 months (range 5.4-144.2) for patients with meningiomas. 73% of deaths were attributed to cancer progression. Overall survival was 35.6% at 1 year and 5.9% at 5 years.
Conclusion: Our study supports the safety and feasibility of reirradiation for select CNS tumor patients, showing acceptable toxicity and encouraging outcomes in recurrent high-grade tumor cases. Longer follow-up and further analyses are needed to better define long-term outcomes and modality-specific efficacy.