Tumor control probability and safety of reirradiation with stereotactic radiosurgery for local recurrence of brain metastases after prior stereotactic radiosurgery: a systematic review and meta-analysis

Stereotactic re-irradiation (re-SRT) is a promising salvage treatment for locally recurrent brain metastases (BMs) after prior stereotactic radiotherapy (SRT), but its feasibility and safety remain insufficiently validated. A systematic search was conducted for studies involving patients who received re-SRT, following PRISMA guidelines. Pooled local control rate (LCR), overall survival (OS), and radiation necrosis (RN) rates were calculated using a random-effects model. Meta-regression analyses were conducted to evaluate the relationship between variables and outcomes. Logistic dose–response models were hypothetically constructed for tumor control probability (TCP) in terms of the biological effective dose using an α/β of 10 Gy (BED 10 ). Fourteen studies (687 patients, 896 BMs) were included, with a median BED 10 of 50.4 Gy. Pooled 1-year LCR and OS rate were 76% (95% CI: 73–79%) and 62% (95% CI: 52–70%), respectively. Pooled RN and symptomatic RN rates were 21% and 10%. BED 10 was positively associated with 1-year LCR ( P = 0.007), with a significant dose-response relationship. Re-SRT is effective for recurrent BMs but carries a relatively high risk of symptomatic RN. Further research on re-SRT combined with innovative therapies (e.g., immunotherapy) is needed to improve efficacy and reduce toxicity.