Department of Proton Therapy, A. Tsyb Medical Radiological Research Centre (MRRC), 4 Korolev Street, Obninsk, Russia, 249036.
Department of Histology, Cytology and Embryology, Medical Institution, People's Friendship University of Russia, Moscow, Russia.
Radiat Oncol. 2021 Dec 20;16(1):238. doi: 10.1186/s13014-021-01961-9.
This study presents an analysis (efficacy and toxicity) of outcomes in patients with skull-base chordomas or chondrosarcomas treated with a fixed horizontal pencil proton beam.
Chordomas (CAs) and chondrosarcomas (CSAs) are rare tumours that are usually located near the base of the skull and very close to the brain's most critical structures. Proton therapy (PT) is often considered the best radiation treatment for these diseases, but it is still a limited resource. Active scanning PT delivered via a fixed pencil beamline might be a promising option.
This is a single-centre experience describing the results of proton therapy for 31 patients with CA (n = 23) or CSA (n = 8) located near the base of the skull. Proton therapy was utilized by a fixed pencil beamline with a chair to position the patient between May 2016 and November 2020. Ten patients underwent resection (32.2%), 15 patients (48.4%) underwent R2 resection, and 6 patients had unresectable tumours (19.4%). In 4 cases, the tumours had been previously irradiated. The median PT dose was 70 GyRBE (relative biological efficacy, 1.1) [range, 60 to 74] with 2.0 GyRBE per fraction. The mean GTV volume was 25.6 cm [range, 4.2-115.6]. Patient demographics, pathology, treatment parameters, and toxicity were collected and analysed. Radiation-induced reactions were assessed according to the Common Terminology Criteria for Adverse Events (CTCAE) v 4.0.
The median follow-up time was 21 months [range, 4 to 52]. The median overall survival (OS) was 40 months. The 1- and 2-year OS was 100%, and the 3-year OS was 66.3%. Four patients died due to non-cancer-related reasons, 1 patient died due to tumour progression, and 1 patient died due to treatment-related injuries. The 1-year local control (LC) rate was 100%, the 2-year LC rate was 93.7%, and the 3-year LC rate was 85.3%. Two patients with CSA exhibited progression in the neck lymph nodes and lungs. All patients tolerated PT well without any treatment interruptions. We observed 2 cases of ≥ grade 3 toxicity, with 1 case of grade 3 myelitis and 1 case of grade 5 brainstem injury.
Treatment with a fixed proton beam shows promising disease control and an acceptable toxicity rate, even the difficult-to-treat subpopulation of patients with skull-base chordomas or chondrosarcomas requiring dose escalation.
本研究对采用固定水平铅笔束质子束治疗颅底脊索瘤或软骨肉瘤患者的疗效和毒性进行了分析。
脊索瘤（CA）和软骨肉瘤（CSA）是罕见的肿瘤，通常位于颅底附近，且非常靠近大脑最关键的结构。质子治疗（PT）通常被认为是治疗这些疾病的最佳放射治疗方法，但它仍然是一种有限的资源。通过固定铅笔束线进行主动扫描的质子治疗可能是一种很有前途的选择。
这是一项单中心经验，描述了 31 例位于颅底附近的 CA（n=23）或 CSA（n=8）患者接受质子治疗的结果。2016 年 5 月至 2020 年 11 月，采用固定铅笔束线和椅子为患者定位进行质子治疗。10 例患者接受了手术切除（32.2%），15 例（48.4%）患者接受了 R2 切除，6 例患者肿瘤无法切除（19.4%）。在 4 例中，肿瘤曾接受过放射治疗。PT 剂量中位数为 70 GyRBE（相对生物效应，1.1）[范围 60-74]，每次分割 2.0 GyRBE。GTV 体积平均为 25.6cm[范围 4.2-115.6]。收集并分析了患者人口统计学、病理学、治疗参数和毒性情况。根据通用不良事件术语标准（CTCAE）v4.0 评估放射性反应。
中位随访时间为 21 个月[范围 4-52]。中位总生存期（OS）为 40 个月。1 年和 2 年的 OS 为 100%，3 年的 OS 为 66.3%。4 例患者因非癌症相关原因死亡，1 例患者因肿瘤进展死亡，1 例患者因治疗相关损伤死亡。1 年局部控制（LC）率为 100%，2 年 LC 率为 93.7%，3 年 LC 率为 85.3%。2 例 CSA 患者出现颈部淋巴结和肺部进展。所有患者均能很好地耐受 PT，无任何治疗中断。我们观察到 2 例≥3 级毒性，其中 1 例为 3 级脊髓炎，1 例为 5 级脑干损伤。
采用固定质子束治疗颅底脊索瘤或软骨肉瘤患者，具有良好的疾病控制效果，且毒性发生率可接受，即使是需要剂量升级的治疗难度较大的颅底脊索瘤或软骨肉瘤患者亚群也是如此。
