Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, United States.
Division of Pediatrics, The University of Texas MD Anderson Cancer Center, Houston, United States.
Radiother Oncol. 2019 May;134:143-150. doi: 10.1016/j.radonc.2019.02.002. Epub 2019 Feb 14.
Pediatric patients with rhabdomyosarcoma (RMS) of the head and neck (H&N) are treated with multimodal therapy, often with radiotherapy (RT) as definitive local therapy. We report on the patterns of failure following proton beam therapy (PBT) for H&N RMS.
Forty-six H&N RMS patients were enrolled on a prospective registry protocol between 2006 and 2015. All were treated with a combination of chemotherapy (ChT) and PBT. Most patients (25 patients, 54%) had parameningeal tumors, of which 11 (24%) had intracranial extension (ICE). Thirteen patients (28%) had primary tumors greater than 5 cm. Median total cyclophosphamide (CPM) equivalent dose was 13.2 g/m (range 0-16.8 g/m). Median RT dose was 50.4 Gy(RBE) (range 36 Gy[RBE]-50.8 Gy[RBE]).
With median follow-up of 3.9 years, five-year overall survival was 76%, and five-year progression-free survival was 57%. Seventeen patients (37%) experienced relapse, including 7 with local failure (LF). Five-year local control (LC) was 84%. Tumor size greater than 5 cm predicted increased risk of LF (hazard ratio [HR] 6.49, p = 0.03), as did the presence of ICE at diagnosis (HR 5.21, p = 0.03). Six relapses occurred in patients with ICE; all included a component of central nervous system relapse, with leptomeningeal disease and/or LF with an intracranial component. Delayed RT delivery after week 4 of ChT predicted increased risk of relapse for ICE patients (HR 10.49, p = 0.006).
PBT confers excellent LC, and a favorable late toxicity profile as compared with prior photon RT data. Our observations support ongoing trial efforts to dose-escalate RT for patients with larger tumors. However, these data raise concerns regarding excess failures among patients with ICE.
头颈部（H&N）横纹肌肉瘤（RMS）的儿科患者接受多模式治疗，通常采用放射治疗（RT）作为确定性局部治疗。我们报告质子束治疗（PBT）治疗 H&N RMS 后的失败模式。
2006 年至 2015 年期间，46 例 H&N RMS 患者入组前瞻性登记研究。所有患者均接受化疗（ChT）和 PBT 的联合治疗。大多数患者（25 例，54%）存在脑脊膜旁肿瘤，其中 11 例（24%）存在颅内延伸（ICE）。13 例（28%）患者的原发肿瘤大于 5cm。环磷酰胺（CPM）等效总剂量中位数为 13.2g/m（范围 0-16.8g/m）。中位放疗剂量为 50.4Gy（RBE）（范围 36Gy[RBE]-50.8Gy[RBE]）。
中位随访 3.9 年后，总 5 年生存率为 76%，无进展 5 年生存率为 57%。17 例（37%）患者复发，包括 7 例局部失败（LF）。5 年局部控制（LC）率为 84%。肿瘤大小大于 5cm 预测 LF 风险增加（风险比[HR]6.49，p=0.03），诊断时存在 ICE 也是如此（HR 5.21，p=0.03）。6 例 ICE 患者发生复发，均包括中枢神经系统复发，伴有脑膜疾病和/或颅内成分的 LF。ChT 第 4 周后延迟 RT 治疗预测 ICE 患者复发风险增加（HR 10.49，p=0.006）。
与既往光子 RT 数据相比，PBT 可获得出色的 LC 和良好的迟发性毒性特征。我们的观察结果支持正在进行的尝试，为更大肿瘤患者增加 RT 剂量。然而，这些数据引起了对 ICE 患者额外失败的关注。
