Introduction: The impact of the dose and fractionation of thoracic radiotherapy on the risk of developing brain metastasis (BM) has not been evaluated prospectively in limited stage SCLC patients receiving prophylactic cerebral irradiation (PCI). Methods: Data from patients treated with PCI from the CONVERT trial were analyzed. Results: Four hundred forty‐nine of 547 patients (82%) received PCI after completion of chemoradiotherapy. Baseline brain imaging consisted of computed tomographic scans in 356 of 449 patients (79%) and magnetic resonance imaging in 83 of 449 (18%) patients. PCI was delivered to 220 of 273 participants (81%) in the twice‐daily (BD) group and 229 of 270 in the once‐daily (OD) group (85%; p = 0.49). Total median PCI dose was 25 Gy in both the BD and OD groups (p = 0.74). In patients who received PCI, 75 (17%) developed BM (35 [8%] in OD and 40 [9%] in BD) and 173 (39%) other extracranial progression. In the univariate analysis, gross tumor volume (GTV) was associated with an increased risk of BM (p = 0.007) or other radiological progression events (p = 0.006), whereas in a multivariate analysis both thoracic GTV (tGTV) and ECOG performance score were associated with either progression type. The median overall survival (OS) of patients treated with PCI was 29 months. In the univariate analysis of OS, PCI timing from end of chemotherapy, weight loss of more than 10%, and tGTV were prognostic factors associated with OS. In the multivariate analysis, only tGTV was associated with OS. Delay between end of chemotherapy and PCI was not associated with OS. Conclusions: Patients receiving OD or BD thoracic radiotherapy have the same risk of developing BM. Larger tumors are associated with a higher risk of BM.

中文翻译：

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局限期小细胞肺癌患者的预防性颅脑照射：前瞻性随机 3 期 CONVERT 试验的次要结果

简介：尚未在接受预防性脑照射 (PCI) 的局限期 SCLC 患者中前瞻性评估胸部放疗的剂量和分割对发生脑转移 (BM) 风险的影响。方法：分析了 CONVERT 试验中接受 PCI 治疗的患者的数据。结果：547 名患者中有 449 名（82%）在完成放化疗后接受了 PCI。基线脑成像包括 449 名患者中的 356 名 (79%) 的计算机断层扫描和 449 名患者中的 83 名 (18%) 的磁共振成像。每日两次 (BD) 组 273 名参与者中的 220 名 (81%) 和每日一次 (OD) 组 270 名参与者中的 229 名 (85%；p = 0.49) 接受了 PCI。BD 和 OD 组的 PCI 总剂量中位数均为 25 Gy（p = 0.74）。在接受 PCI 的患者中，75 (17%) 人发展为 BM（OD 35 [8%] 和 BD 40 [9%]）和 173 (39%) 其他颅外进展。在单变量分析中，总肿瘤体积 (GTV) 与 BM (p = 0.007) 或其他放射学进展事件 (p = 0.006) 的风险增加相关，而在多变量分析中，胸廓 GTV (tGTV) 和 ECOG 表现评分与任一进展类型相关。接受 PCI 治疗的患者的中位总生存期 (OS) 为 29 个月。在 OS 的单变量分析中，化疗结束后的 PCI 时间、体重减轻超过 10% 和 tGTV 是与 OS 相关的预后因素。在多变量分析中，只有 tGTV 与 OS 相关。化疗结束和 PCI 之间的延迟与 OS 无关。结论：接受 OD 或 BD 胸部放疗的患者发生 BM 的风险相同。较大的肿瘤与较高的 BM 风险相关。