PURPOSE Stereotactic radiosurgery (SRS) is typically considered for patients who cannot undergo surgical resection for large (> 10 cm3) brain metastases (BMs). Staged SRS requires adaptive planning during each stage of the irradiation period for improved tumor control and reduced radiation damage. However, there has been no study on the tumor reduction rates of this method. We evaluated the outcomes of two-stage SRS across multiple primary cancer types. METHODS We analyzed 178 patients with 182 large BMs initially treated with two-stage SRS. The primary cancers included breast (BC), non-small cell lung (NSCLC), and gastrointestinal tract cancers (GIC). We analyzed the overall survival (OS), neurological death, systemic death (SD), tumor progression (TP), tumor recurrence (TR), radiation necrosis (RN), and the tumor reduction rate during both stages. RESULTS The median survival time after the first Gamma Knife surgery (GKS) procedure was 6.6 months. Compared with patients with BC and NSCLC, patients with GIC had shorter OS and a higher incidence of SD. Compared with patients with NSCLC and GIC, patients with BC had significantly higher tumor reduction rates in both sessions. TP rates were similar among primary cancer types. There was no association of the tumor reduction rate with tumor control. The overall cumulative incidence of RN was 4.2%; further, the RN rates were similar among primary cancer types. CONCLUSIONS Two-stage SRS should be considered for BC and NSCLC if surgical resection is not indicated. For BMs from GIC, staged SRS should be carefully considered and adapted to each unique case given its lower tumor reduction rate and shorter OS.

中文翻译：

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原发性癌症中较大脑转移的两阶段伽玛刀放射外科手术结果的比较。

目的立体定向放射外科手术（SRS）通常用于无法进行大（> 10 cm3）脑转移（BMs）手术切除的患者。分阶段的SRS需要在辐射期的每个阶段进行适应性规划，以改善肿瘤控制和减少辐射损伤。但是，尚未对该方法的肿瘤减少率进行研究。我们评估了多种原发癌类型的两阶段SRS的结果。方法我们分析了178例最初接受两阶段SRS治疗的182例大型BM患者。原发性癌症包括乳腺癌（BC），非小细胞肺癌（NSCLC）和胃肠道癌（GIC）。我们分析了总生存期（OS），神经系统死亡，系统性死亡（SD），肿瘤进展（TP），肿瘤复发（TR），放射坏死（RN），以及这两个阶段的肿瘤减少率。结果首次伽玛刀手术（GKS）手术后的中位生存时间为6.6个月。与BC和NSCLC患者相比，GIC患者OS较短，SD发生率较高。与NSCLC和GIC患者相比，BC患者在这两个阶段的肿瘤减少率均明显更高。在原发性癌症类型中，TP率相似。肿瘤减少率与肿瘤控制没有关联。RN的总累积发生率为4.2％；此外，在原发性癌症类型中，RN率相似。结论如果不进行手术切除，应考虑对BC和NSCLC进行两期SRS治疗。对于来自GIC的BM，