Division of Stereotactic and Functional Neurosurgery, Department of Neurosurgery, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, CA 90095-7039, USA.
Int J Radiat Oncol Biol Phys. 2012 Jun 1;83(2):542-51. doi: 10.1016/j.ijrobp.2011.08.004. Epub 2011 Dec 2.
Intracranial chordomas and chondrosarcomas are histologically low-grade, locally invasive tumors that infiltrate the skull base. Currently, consensus therapy includes surgical resection and adjuvant radiotherapy. Radiation delivery is typically limited by the proximity of these tumors to critical skull base structures.
This is a retrospective review of 13 cases of chordomas and 2 cases of chondroid chondrosarcomas of the skull based treated with linear accelerator stereotactic radiotherapy (SRT, n = 10) or stereotactic radiosurgery (SRS, n = 5). The average time to the most recent follow-up visit was 4.5 years. The tumor characteristics, treatment details, and outcomes were recorded. Each radiation plan was reviewed, and the dosage received by the brainstem, optic apparatus, and pituitary was calculated.
Of the 10 patients treated with SRT, 6 were found to have unchanged or decreased tumor size as determined from radiographic follow-up. Of the 5 patients treated with SRS, 3 were found to have stable or unchanged tumors at follow-up. The complications included 1 SRT patient who developed endocrinopathy, 2 patients (1 treated with SRS and the other with SRT), who developed cranial neuropathy, and 1 SRS patient who developed visual deficits. Additionally, 1 patient who received both SRS and SRT within 2 years for recurrence experienced transient medial temporal lobe radiation changes that resolved.
Where proton beam therapy is unavailable, linear accelerator-based SRT or radiosurgery remains a safe option for adjuvant therapy of chordomas and chondrosarcomas of the skull base. The exposure of the optic apparatus, pituitary stalk, and brainstem must be considered during planning to minimize complications. If the optic apparatus is included in the 80% isodose line, it might be best to fractionate therapy. Exposure of the pituitary stalk should be kept to <30 Gy to minimize endocrine dysfunction. Brainstem exposure should be limited to <60 Gy in fractions.
颅内脊索瘤和软骨肉瘤在组织学上属于低级别、局部侵袭性肿瘤，可浸润颅底。目前，共识治疗包括手术切除和辅助放疗。由于这些肿瘤靠近颅底关键结构，放射治疗的实施通常受到限制。
这是一项对 13 例颅底脊索瘤和 2 例软骨样软骨肉瘤患者的回顾性研究，他们接受了直线加速器立体定向放疗（SRT，n=10）或立体定向放射外科治疗（SRS，n=5）。最近一次随访的平均时间为 4.5 年。记录了肿瘤特征、治疗细节和结果。对每个放射治疗计划进行了回顾，并计算了脑干、视神经和垂体接受的剂量。
在接受 SRT 治疗的 10 例患者中，有 6 例根据影像学随访发现肿瘤大小不变或缩小。在接受 SRS 治疗的 5 例患者中，有 3 例在随访时发现肿瘤稳定或不变。并发症包括 1 例 SRT 患者发生内分泌疾病，2 例（1 例接受 SRS 治疗，另 1 例接受 SRT 治疗）患者发生颅神经病变，1 例 SRS 患者发生视力障碍。此外，1 例患者在 2 年内因复发先后接受 SRS 和 SRT 治疗，出现短暂性内侧颞叶放射改变，随后缓解。
在质子束治疗不可用的情况下，基于直线加速器的 SRT 或放射外科仍然是颅底脊索瘤和软骨肉瘤辅助治疗的安全选择。在计划中必须考虑视神经、垂体柄和脑干的暴露情况，以尽量减少并发症。如果视神经包括在 80%等剂量线内，最好进行分次治疗。垂体柄的照射应保持在<30Gy 以下，以尽量减少内分泌功能障碍。脑干的照射应限制在<60Gy 以下。
