Outcomes and adverse events of postoperative stereotactic interventional radiotherapy/brachytherapy for brain metastases: a systematic review.

Postoperative radiotherapy is commonly used after resection of brain metastases, but durable local control with a low rate of adverse events (AEs) remains challenging. This systematic review summarizes outcomes and AEs of postoperative stereotactic interventional radiotherapy (S-IRT; brachytherapy) for resected brain metastases. PubMed, Embase, Scopus, and Web of Science were searched through June 30, 2024. No review protocol was registered. Eligible studies reported postoperative S-IRT after metastasis resection. Data were extracted independently by two reviewers, with disagreements resolved by consensus. Risk of bias and methodological quality were assessed using the Newcastle-Ottawa Scale and MINORS. Because of clinical and methodological heterogeneity, results were synthesized narratively, and no meta-analysis was performed. Eighteen studies (9 prospective, 8 retrospective, 1 case series) including 542 patients were eligible. Eleven studies used Cs-131, six used I-125, and one used both. Prescribed doses ranged from 60 to 80 Gy, usually at a depth of 5 mm. One-year local control ranged from 83 to 100%. Symptomatic radionecrosis occurred in 4.6% of Cs-131 and 9% of I-125 implants; leptomeningeal disease rates were 1.6% and 12.5%, respectively. Postoperative S-IRT appears promising, but most studies were non-comparative and heterogeneous, so findings should be considered hypothesis-generating.