BACKGROUND AND OBJECTIVE A retrospective review of consecutive patients between January 2012 and December 2018 receiving hypofractionated stereotactic radiotherapy (HSRT) to the cavity after resection for brain metastases was performed. METHODS Treatment was delivered using an appropriately commissioned linear accelerator. The primary outcome was time to radiological or histological confirmation of local recurrence following completion of HSRT. Dose-fractionation regimens were converted to biologically 2 Gy-equivalent doses assuming α/β = 10 (EQD2[10]). Multivariate Cox proportional hazards modelling was performed to determine hazard ratios (HR) with respective 95% confidence intervals (CI). The Log-rank test was used to determine p values taking statistical significance p < 0.05. RESULTS There were 134 patients and 144 cavities identified. The most common primary histologies were melanoma (n = 49) and lung (n = 32). 116 patients (87%) underwent a gross total resection. Median planning target volume (PTV) was 28 cm3 (range 2.4-149.2). Median EQD2[10] was 38.4 Gy (range 22.3-59.7) and 24 Gy in 3 fractions was the most common regimen. 12 (9%) patients demonstrated local recurrence at median interval 215 days (range 4-594). 7 (5%) patients experienced grade 3 or higher toxicities. In multivariate analysis, EQD2[10] was associated with local failure such that increased equivalent doses improved local control [HR = 0.79 and 95% CI 0.65-0.96, p = 0.0192]. There were no significant associations for primary histology, patient age, volume of residual disease, PTV volume or location. CONCLUSION This large series demonstrates that HSFRT to the surgical resection cavity for brain metastases has improved local control with increasing dose. Rates of grade 3 or higher toxicity were low overall.

中文翻译：

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进行脑转移手术后，对腔进行低等立体定向放射治疗后剂量反应的证据。

背景与目的回顾性分析2012年1月至2018年12月连续切除脑转移瘤的患者接受腔内立体定向放射治疗（HSRT）的方法。方法使用适当调试的线性加速器进行治疗。主要结局是在完成HSRT后需要影像学或组织学确认局部复发的时间。假定α/β= 10（EQD2 [10]），剂量分级方案已转换为生物学上2 Gy等效剂量。进行多变量Cox比例风险建模以确定具有95％置信区间（CI）的风险比（HR）。对数秩检验用于确定p值，其统计显着性p <0.05。结果确定了134例患者和144个腔。最常见的原发性组织学是黑色素瘤（n = 49）和肺部（n = 32）。116例（87％）患者接受了全切除术。中位数计划目标体积（PTV）为28 cm3（范围2.4-149.2）。EQD2 [10]的中位数为38.4 Gy（范围22.3-59.7），最常见的治疗方案是3分24 Gy。12名（9％）患者在中位间隔215天（范围4-594）表现出局部复发。7名（5％）患者经历了3级或更高的毒性。在多变量分析中，EQD2 [10]与局部衰竭相关，因此增加等效剂量可以改善局部控制[HR = 0.79和95％CI 0.65-0.96，p = 0.0192]。原始组织学，患者年龄，残留疾病量，PTV量或位置均无明显关联。结论该大系列研究表明，针对脑转移瘤的手术切除腔的HSFRT随着剂量的增加而改善了局部控制。总体上，3级或更高毒性的发生率较低。