RADI-02. SINGLE-SESSION VERSUS MULTISESSION GAMMA KNIFE RADIOSURGERY FOR LARGE BRAIN METASTASES FROM NON-SMALL CELL LUNG CANCER: 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), the authors retrospectively analyzed the clinical outcomes of the 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 cm(3) 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 cm(3) (range, 10.0–58.3). 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% versus 45.4%, p = 0.83). While eight 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 to preserve neurological function.