Outcome of Brain Metastases Treated with Gamma Knife Stereotactic Radiosurgery: A Retrospective Cohort Study of 205 Cases

-BACKGROUND: Brain metastases (BMs) are the most common expansive intracranial lesions in adults. Approx-imately 50% of patients diagnosed with new BMs will have >1 BM at the diagnosis. We report our experience with BMs treated with Leksell Gamma Knife stereotactic radi-osurgery (GKSR) and evaluate the outcomes. -METHODS: Patients treated by GKSR in our institution between 2008 and 2021 for BMs were evaluated retrospectively. -RESULTS: A total of 205 patients (56.6% women) were included, with a median age of 59 years (range, 25-83 years). The breast (n = 85; 42.5%) and lung (n = 76; 38%) were the most common original locations for the primary tumors. Of the 205 patients, 103 (50.3%) had a single BM and 102 (49.7%) had & DDAG;2 BMs. The median number of mul-tiple BMs treated was 4 (range, 2-43). The mean overall survival (OS) time was 6.00 months (95% confidence in-terval [CI], 5.07-6.93 months) for all BMs. The median rate of tumor control after radiosurgery was 65% (range, 20%-99%) during a median follow-up of 6.00 months (95% CI, 3-84 months). In the overall population, the 1-, 2-, and 5-year OS rate was 37.55%, 25.12%, and 18.51%, respectively. The mean OS time was longer for those with multiple BMs than for those with a single BM (mean, 10 months [95% CI, 6.67-13.33 months] vs. mean, 5 months [95% CI, 4.21-5.70 months]; P = 0.03). Retreatment, tumor stability (control), and progression influenced the OS of patients with BMs, whether single or multiple (P < 0.001). -CONCLUSIONS: GKSR provides good results in terms of OS and better quality of life for patients with BMs, whether single or multiple. Tumor stability and retreatment influ-enced the OS of patients with BMs.