Reirradiation outcomes following salvage conventionally fractionated Gamma Knife stereotactic radiotherapy (SFGK) to recurrent primary non-glial brain tumors.

Abstract

PurposeTo evaluate the efficacy and safety of salvage conventionally fractionated Gamma Knife stereotactic radiotherapy (SFGK) reirradiation for recurrent, previously irradiated primary non-glial brain tumours.MethodsConsecutive patients underwent SFGK from 2019 to 2024 for progressive, previously definitively irradiated primary intracranial tumours. The primary endpoint was local progression-free survival (LPFS). Secondary endpoints were overall survival (OS) and safety.ResultsTwenty-six patients (44 tumours) were treated. There were 34 meningiomas (77%), of which 28 were WHO Grade 2. The median time from prior radiotherapy was 50.4 months (IQR 19.7-86.8). The SFGK prescription dose was 50.4 Gy in 28 fractions in 37 tumors (84%). The median cumulative prescription EQD2 was 102.7 Gy (IQR 99.6-114.6) for those with one prior radiotherapy course. The median normal brain EQD2 was 99.2 Gy (97.9-117.5) for those with one prior radiotherapy course. The median follow-up was 18.1 months (IQR 10.5-28.2). Overall LPFS at 12 and 24 months was 91.0% (95% CI 73.6-97.2%) and 75.1% (95% CI 51.0-88.6%), respectively. OS at 12 and 24 months was 96.2% (95% CI 75.7-99.4%) and 83.2% (95% CI 54.8-94.6%), respectively. For the meningioma cohort, 12- and 24-month LPFS was 90.6% (95% CI 65.7-97.7%) and 74.1% (95% CI 42.7-90.0%), respectively. Grade 3 radionecrosis occurred in two patients (6.9%), one case of Grade 3 progressive intracranial hemorrhage (3.4%), and no Grade 4 or 5 events were observed.ConclusionsSFGK re-irradiation is feasible and well tolerated, achieving durable local control in recurrent non-glial brain tumours with few serious adverse events despite high cumulative doses.