Stereotactic radiotherapy for brain metastases in patients with non-small cell lung cancer: CyberKnife-M6 experience.

Background: We assessed local control and survival in non-small cell lung cancer (NSCLC) patients with limited brain metastases (BM) who underwent stereotactic radiotherapy (SRT) using the CyberKnife-M6 (CK-M6) system as well as the treatment efficacy. Materials and Methods: Twenty NSCLC patients with 40 BM were treated between 2018 and 2020. Median age was 61 years (46-80 years). Surgery was performed for nine lesions in eight cases. Median lesion size was 10 mm (2-38 mm). Resection cavities and intact metastases contoured as gross target volume. Planning target volume (PTV) was created with a margin of 0-2 mm. A median of 18 Gy (18-20 Gy) in one fraction was applied to 19 lesions, and 25 Gy/5 fractions (24-30 Gy/3-6 fx) to 21 lesions. Median treatment time was 20 min (13-35 min). Results: The median follow-up duration was nine months (1-15 months) in March 2021. Prescription isodose covering 95% of PTV was 85,9% (80% -92,7%). During the follow-up, local and intracranial control rates in evaluated patients were 88% (15/17) and 70,5% (12/17), respectively. Asymptomatic radionecrosis was observed in 23.5% (4/17) of patients at a median of 8 months (6-12 months). The median survival was 13 months (1-25 months). In univariate analysis, factors positively affecting survival were Karnofsky performance status, RPA, and DS-GPA classification (p < 0,05). Conclusion: Promising local control and survival in patients and treatment time demonstrated that CK-M6 based SRT was effective, safe and comfortable in the treatment of NSCLC with BM. [ABSTRACT FROM AUTHOR]