Comparison of treatment outcomes of single-session and 2-stage gamma knife surgery for large brain metastases from lung adenocarcinoma

PURPOSE To compare the therapeutic outcomes of single-session gamma knife surgery (GKS) and 2-stage GKS for large (diameter ≥ 2 cm) brain metastases from lung cancer. METHODS For the first time, patients with brain metastases from a single primary tumor were selected, and the treatment data of patients with large lung brain metastases from lung adenocarcinoma treated with single-session or 2-stage GKS between January 2019 and June 2022 at our hospital were retrospectively analyzed. Seventy-seven patients (85 lesions) were in the single-session GKS group, while 62 patients (72 lesions) were in the 2-stage GKS group. Propensity score matching of cases was performed because of differences in the number of patients and clinical factors prior to GKS between the two groups. Finally, 90 patients (45 in each group) were included in the matched case-control study. Therapeutic outcomes were measured based on the Karnofsky performance status score, local tumor control, cumulative incidence of radiation necrosis, and overall survival of each patient. RESULTS In the overall patient cohort, the cumulative incidence of radiation necrosis was significantly lower in the staged GKS group than in the single-session GKS group (5.0% vs. 18.4% at 1 year, p  = 0.028). In the case-matched cohort, the cumulative incidence of neurological death was significantly lower in the staged GKS group than in the single-session GKS group (2.4% vs. 4.9% at 1 year, p  = 0.045). In both the overall and case-matched cohorts, the rate of tumor volume change after GKS was significantly higher in the staged GKS group (67.5%, 67.5%) than in the single-session GKS group (53.0, 51.1%) ( p  < 0.05). The local tumor control and rate of tumor volume change were also significantly better in the staged GKS group than in the single-session GKS group. No significant difference in overall survival was observed between the two groups. Besides, the rate of tumor volume change is a significant factor that influences the long-term efficacy of local tumor control. Additionally, the control of the primary tumor is an independent influencing factor for the overall survival of patients. CONCLUSION Our findings suggest that staged GKS is safer and more efficacious than single-session GKS for large brain metastases (≥ 2 cm in diameter) from lung adenocarcinoma, and that the rate of tumor volume change after treatment influences local tumor progression.