Stereotactic radiotherapy vith CyberKnife-M6 in patients with limited brain metastases originated from lung cancer

Abstract

Abstract Purpose The effect of stereotactic radiotherapy (SRT) with CyberKnife-M6 (CK-M6) on local control (LC) and overall survival (OS) in patients with limited brain metastases (BM) originated from lung cancer was investigated.Methods A total of 64 BM of the 35 patients were treated between 2018 to 2022. The median age was 63 (39–80). Median lesion size was 11 mm (2–40). Resection cavity or intact metastasis was contoured as gross target volume. Planning target volume (PTV) was created with 0–2 mm margin. A median of 24 Gy in 3 fractions (18–30/1–6) was applied to 64 lesions. Median treatment duration was 19 min (12–35).Results The median follow-up was 13 months (1–48) at February 2023. The median prescription isodose covering 95% of PTV was 86.1% (80- 95.01%). During the follow-up, LC was obtained as 70% (39/56) in the evaluated lesions. Asymptomatic radionecrosis was observed in 20% (11/56) of lesions at a median of 9 months (6–20). The mean OS from SRT was 20 months (± 2,92). In multivariate analysis, disease-specific graded prognostic assesment score ≤ 2 (p = 0.043, HR: 3,11, 95% CI: 1,03–9,93), treatment duration ≤ 19 min (p = 0.021, HR: 2.29, 95% CI: 1,13 − 4,64) and absence of LC at 12 months (p = 0,007, HR: 5,46, 95% CI: 1,57 − 18,97) were unfavorable factors in terms of OS.Conclusion With a median treatment duration of 19 min, CK-M6 based cranial SRT was found to be effective, safe and comfortable.