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

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.

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).

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).

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.