Hafiz Asif Iqbal*, Rolina K. Alwassia, Zaheeda Mulla, Ahmed AbdelKhalek Hussein and Hane Mohammad Muamenah
Objective: To analyze the post-re-RT progression-free survival (PFS) and incidence of radio-necrosis (BRN) in patients with recurrent primary brain tumors and to explore the associated factors.
Method: A retrospective cohort study that included 15 pediatric and adult patients with primary brain tumors who were treated with re-RT between 2011 and 2020. The study endpoints included the post-re-RT PFS, which were analyzed using Kaplan-Meier survival analysis, and the incidence of radio-necrosis. Baseline demographic and clinical data, primary radiation therapy (RT1) parameters and outcomes, and re-RT parameters and outcomes, were analyzed as factors for the two outcomes.
Result: Of the 15 participants, 7 had glioblastoma and 5 had anaplastic ependymoma. The mean interval from first RT to re-RT was 24 months (range=2-60 months). The mean total cumulative dose after re-RT as per EQD2 (equivalent dose in 2 Gy) fractions was 101.97 Gy (max 135.6 Gy). The total mean (max) cumulative doses for organs at risk as per EQD2 after re-RT were 54.05 (92.93) Gy for brain stem, 41.19 (87.94) Gy for optic chiasma, and 28.79 (77.18) Gy and 28.6 (88.71) Gy for left and right optic nerves respectively. Disease progression occurred in 10/15 patients, and the median PFS was 4 months (95%CI=0-9.1). Although not statistically significant, PFS was likely to be prolonged in case of low-grade tumors, longer RT1-re-RT time. Radiation necrosis occurred in 2 patients.
Conclusion: The expected clinical benefits against the adverse effects should be contemplated for re-irradiation in primary brain tumors.
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