Objectives: Lung cancer is one of the most common malignancies and the leading cause of death from cancer in the world. In patients with NSCLC, patients with brain metastases have a higher rate of EGFR gene mutations than others, and the infrequency of brain metastasis of NSCLC with genetic mutations outperformed the group without mutations. In the past, brain metastasis was known to be a poor prognostic factor, but with the advancement of medicine, especially the introduction of targeted therapy and radiosurgery, outcomes have been significantly improved, including survival and symptom control. Our study aims to evaluate the outcome of Gamma Knife radiosurgery combined TKIs for brain metastasis of non-small cell lung cancer with EGFR gene mutations.

Methods: We analyzed 35 patients with brain metastatic non-small cell lung cancer with EGFR gene mutations from July 2019 to May 2024. Selected patients have brain metastases from 1 to 10 tumors, size ≤ 3cm, KPS score ≥ 60, EGFR gene mutation, first-generation TKI treatment. Patients were treated by stereotactic radiosurgery using Leksell Gamma Knife ICON unit (Elekta AB) with dose of 20 – 24, 18 – 20Gy for lesions measuring < 2, 2.1 – 3 cm, respectively. Patients take 1^st generation TKIs (erlotinib or gefitinib) 1 tablet per day. Patients were assessed for clinical symptoms and imaging response according to RANO criteria at 6, 12 months and survival outcomes.

Results: In our study, cerebral progression-free survival rate at 12 months was 100%, 24 months was 65,6%. Overall survival rate at 12 months was 84%, 24 months was 57,9%, overall survival time was 28 ± 3,7 months.

Conclusion: Combination Gamma Knife radiosurgery with TKIs is an effective treatment for brain metastasis of non-small cell lung cancer with EGFR gene mutations

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