BACKGROUND Gamma knife (GK) and linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) both offer excellent local control in the management of multiple brain metastases. The efficacy and toxicity of LINAC and GK SRS have not been directly compared in the modern era. We studied outcomes in patients treated with LINAC SRS and GK at two separate institutions. METHODS We identified patients treated with either LINAC or GK who were treated to ≥2 lesions and had available follow up. LINAC patients were treated using single-isocenter multitarget technique. We used Cox regression, Fine and Gray competing risks regression, and nearest neighbor propensity score matching to account for confounders and imbalance between cohorts. Kaplan-Meier curves were used to estimate overall survival and rates of radionecrosis. RESULTS We identified 391 patients who were treated in 537 courses to a total 2699 lesions (LINAC: 1014, GK: 1685). After propensity score matching, GK was associated with similar overall survival (HR = 0.86; 95% CI 0.59-1.24; p = 0.41) and higher rate of radionecrosis (HR = 3.83; 95% CI 1.66-8.84; p = 0.002) compared to LINAC. In a secondary propensity score matched analysis comparing radionecrosis in single-fraction LINAC and GK, GK remained associated with higher incidence of radionecrosis (HR = 4.42; 95% CI 1.28-15.29; p = 0.019). CONCLUSIONS In this multi-institutional study, we found similar overall survival with lower incidence of radionecrosis in patients treated with LINAC compared to GK SRS. These findings are hypothesis generating and should be validated in an independent cohort.

中文翻译：

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与伽玛刀相比，基于直线加速器的放射外科治疗与较低的放射性坏死发生率相关，用于治疗多发性脑转移

背景伽玛刀 (GK) 和基于直线加速器 (LINAC) 的立体定向放射外科 (SRS) 都在多发脑转移瘤的管理中提供了出色的局部控制。LINAC 和 GK SRS 的疗效和毒性在现代尚未直接进行比较。我们研究了在两个不同机构接受 LINAC SRS 和 GK 治疗的患者的结果。方法 我们确定了接受 LINAC 或 GK 治疗的患者，这些患者的病灶≥2 个并有可用的随访。LINAC 患者使用单等中心多靶点技术进行治疗。我们使用 Cox 回归、Fine 和 Gray 竞争风险回归以及最近邻倾向得分匹配来解释队列之间的混杂因素和不平衡。Kaplan-Meier 曲线用于估计总体存活率和放射性坏死率。结果 我们确定了 391 名患者，他们在 537 个疗程中接受了治疗，共有 2699 个病灶（LINAC：1014，GK：1685）。倾向评分匹配后，GK 与相似的总生存期（HR = 0.86；95% CI 0.59-1.24；p = 0.41）和较高的放射性坏死率（HR = 3.83；95% CI 1.66-8.84；p = 0.002）相关到 LINAC。在比较单次 LINAC 和 GK 中放射性坏死的次要倾向评分匹配分析中，GK 仍然与较高的放射性坏死发生率相关（HR = 4.42；95% CI 1.28-15.29；p = 0.019）。结论 在这项多机构研究中，我们发现与 GK SRS 相比，接受 LINAC 治疗的患者具有相似的总生存率，但放射性坏死的发生率较低。这些发现是假设产生的，应该在一个独立的队列中得到验证。