Orukari Inema, Perkins Stephanie, Zhao Tianyu, Huang Jiayi, Caruthers Douglas F, Duriseti Sai
Washington University in St. Louis School of Medicine, St. Louis, Missouri, USA.
Department of Radiation Oncology, Washington University School of Medicine/Barnes Jewish Healthcare, St. Louis, Missouri, USA.
Int J Part Ther. 2022 Jun 3;9(1):12-17. doi: 10.14338/IJPT-22-00008.1. eCollection 2022 Summer.
Cranial radiation therapy remains an integral component of curative treatment for pediatric patients with brain tumors. Proton beam radiation therapy (PBT) can limit collateral radiation dose to surrounding normal tissue, thus reducing off-target exposure while maintaining appropriate tumor coverage. While PBT offers significant advantages over photon therapy for pediatric patients with intracranial malignancies, cases of brainstem necrosis after PBT have raised concerns that PBT may pose an increased risk of necrosis over photon therapy. We investigated the incidence of brainstem necrosis at our institution in children treated with PBT for intracranial malignancies.
Patients with pediatric brain tumor treated with passively scattered PBT, using a gantry-mounted, synchrocyclotron single-vault system between 2013 and 2018, were retrospectively reviewed. Inclusion criteria included patients 21 years of age or younger who received a minimum 0.1 cm maximum brainstem dose of 50 Gray relative biological effectiveness (GyRBE). Patients were assessed for "central nervous system necrosis" in the brainstem per the Common Terminology Criteria for Adverse Events (CTCAE), version 5.0 (US National Cancer Institute, Bethesda, Maryland) criteria.
Fifty-eight patients were included for analysis. The median age was 10.3 years. Twenty-one (36.2%) patients received craniospinal irradiation. Thirty-four (58.6%) patients received chemotherapy. The median prescription radiation dose was 54 GyRBE. Regarding published dosimetric constraints used at 3 separate proton centers, the goal brainstem D50% <52 GyRBE was exceeded in 23 (40%) patients, but the brainstem Dmax <58 GyRBE was not exceeded in any patients. No patient experienced grade ≥2 brainstem injury. One patient demonstrated radiographic changes consistent with grade 1 toxicity. This patient had myeloablative chemotherapy with tandem stem cell rescue before PBT.
Our data demonstrates a low risk of any brainstem injury in children treated with passively scattered PBT using a single-vault synchrocyclotron.
对于患有脑肿瘤的儿科患者，颅脑放射治疗仍然是根治性治疗的一个重要组成部分。质子束放射治疗（PBT）可以限制对周围正常组织的附带辐射剂量，从而减少非靶区照射，同时保持对肿瘤的适当覆盖。虽然PBT相对于光子治疗为患有颅内恶性肿瘤的儿科患者提供了显著优势，但PBT后发生脑干坏死的病例引发了人们对PBT可能比光子治疗带来更高坏死风险的担忧。我们调查了在我们机构接受PBT治疗颅内恶性肿瘤的儿童中脑干坏死的发生率。
回顾性分析了2013年至2018年间使用龙门式同步回旋加速器单室系统接受被动散射PBT治疗的小儿脑肿瘤患者。纳入标准包括年龄在21岁及以下、接受的脑干最大剂量至少为0.1厘米、相对生物效应剂量（GyRBE）为50格雷的患者。根据不良事件通用术语标准（CTCAE）第5.0版（美国国立癌症研究所，马里兰州贝塞斯达）标准，对患者的脑干“中枢神经系统坏死”情况进行评估。
58例患者纳入分析。中位年龄为10.3岁。21例（36.2%）患者接受了全脑全脊髓照射。34例（58.6%）患者接受了化疗。中位处方放射剂量为54 GyRBE。关于在3个不同质子中心使用的已发表剂量学限制，23例（40%）患者的目标脑干D50%超过了<52 GyRBE，但没有患者的脑干Dmax超过<58 GyRBE。没有患者经历≥2级脑干损伤。1例患者表现出与1级毒性一致的影像学改变。该患者在PBT前接受了清髓性化疗并进行了串联干细胞救援。
我们的数据表明，使用单室同步回旋加速器进行被动散射PBT治疗的儿童发生任何脑干损伤的风险较低。
