CyberKnife-based stereotactic radiosurgery or fractionated stereotactic radiotherapy in older patients with brain metastases from non-small cell lung cancer

Purpose: We analyzed clinical results of CyberKnife (CK)-based stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) in older patients (age =65 years) affected by brain metastases (BM) from non-small cell lung cancer (NSCLC). Materials and Methods: Forty-three older patients with 92 BM were treated with CK-based SRS/ FSRT at our institution between 2009 and 2019. The end-point was overall survival (OS). Univariate and multivariate analyses were performed to identify the prognostic factors influencing OS. The infield local control (IFLC) within the SRS/FSRT field was also assessed. Results: During a median follow-up period of 18 months, the median OS was 32 months. NSCLC-specific graded prognostic assessment (GPA) (p = 0.027) was an independent significant factor affecting OS in the multivariate analysis. The median IFLC period was 31 months, and the total BM volume (p = 0.025) appeared to be a significant feature of IFLC. No adverse events >grade 2 were reported after SRS/FSRT. Conclusion: CK-based SRS/FSRT is a safe and efficient option for older patients with BM arising from NSCLC, showing good OS without severe side effects. GPA, which was consisted in age, performance status, extra-cerebral metastasis, and number of BM, seemed to be predictive factors for OS.