Radiation-induced malignancies after stereotactic radiosurgery for brain arteriovenous malformations: a large single-center retrospective study and systematic review.

Stereotactic radiosurgery (SRS) is widely utilized to treat small- and medium-sized brain arteriovenous malformations (BAVMs); however, radiation-induced malignancies (RIMs) have been reported as extremely rare yet potentially life-threatening complications of SRS. This study aimed to investigate the risk of RIMs after SRS for BAVMs. The outcomes of patients who underwent single-session SRS for BAVMs at our institution and were followed for ≥ 5 years were analyzed to calculate the incidence of RIMs. In addition, a systematic review was conducted using the existing literature reporting RIMs after SRS for BAVMs in compliance with the PRISMA guideline. Regarding the in-hospital analysis, only one (0.18%) RIM (gliosarcoma) was observed among 569 patients, with a median follow-up period of 151 months (interquartile range, 103-255 months). The 15, 20, and 25-year cumulative incidences of RIMs were 0%, 0%, and 1.01%, respectively, whereas the overall incidence rate was 0.12 per 1,000 patient-years. In the systematic review, 14 studies were included, with the incidence of RIMs ranging from 0.00 to 0.24%. Eight patients with RIMs were identified, and the most common pathology was glioblastoma. The median time until the diagnosis of RIM was 7.1 years (range, 4-19 years) after SRS, and their clinical courses were largely dismal, with the post-diagnosis survival periods being 1-10 months. RIM constitutes an extremely rare but potentially fatal complication following SRS for BAVMs, with its incidence rate being at most 0.24%.