Single-Session versus Multisession Gamma Knife Radiosurgery for Large Brain Metastases from Non-Small Cell Lung Cancer: A Retrospective Analysis.

PURPOSE: To evaluate the efficacy of Gamma Knife radiosurgery (GKS) in patients with large brain metastases by comparing single-session radiosurgery (S-GKS) and multisession radiosurgery (M-GKS), we retrospectively analyzed the clinical outcomes of patients who underwent GKS for brain metastases from non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Between January 2010 and December 2016, 66 patients with 74 lesions ≥10 cm3 from large brain metastases from only NSCLC were included. Fifty-five patients with 60 lesions were treated with S-GKS; 11 patients with 14 lesions were treated with M-GKS. Median doses were 16 Gy (range, 11-18 Gy) for the S-GKS group and 8 Gy (range, 7-10 Gy) in three fractions for the M-GKS group. RESULTS: With a mean follow-up period of 13.1 months (range, 1.3-76.4 months), the median survival duration was 21.1 months for all patients. Median tumor volume was 14.3 cm3 (range, 10.0-58.3 cm3). The local control rate was 77.0% and the progression-free survival rate was 73.6% at the last follow-up. There were no significant between-group differences in terms of local control rate (p = 0.10). Compared with S-GKS, M-GKS did not differ significantly in radiation-induced complications (38.1 vs. 45.4%, p =0.83). While 8 patients who underwent S-GKS experienced major complications of grade ≥3, no toxicity was observed in patients treated with M-GKS. CONCLUSIONS: M-GKS may be an effective alternative for large brain metastases from NSCLC. Specifically, severe radiation-induced toxicity (≥grade 3) did not occur in M-GKS for large-volume metastases. Although the long-term effects and results from larger samples remain unclear, M-GKS may be a suitable palliative treatment for preserving neurological function.