Dhayalan Dhanushan, Perry Avital, Graffeo Christopher S, Tveiten Øystein Vesterli, Muñoz Casabella Amanda, Pollock Bruce E, Driscoll Colin L W, Carlson Matthew L, Link Michael J, Lund-Johansen Morten
1Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.
3Department of Clinical Medicine, University of Bergen, Norway; and.
J Neurosurg. 2022 Jul 29;138(2):420-429. doi: 10.3171/2022.5.JNS22249. Print 2023 Feb 1.
The goal of microsurgical resection of vestibular schwannoma (VS) is gross-total resection (GTR) to provide oncological cure. However, a popular strategy is to halt the resection if the surgical team feels the risk of cranial nerve injury is imminent, achieving a maximally safe subtotal resection (STR) instead. The tumor remnant can then be treated with stereotactic radiosurgery (SRS) once the patient has recovered from the immediate postoperative period, or it can be followed with serial imaging and treated with SRS in a delayed fashion if residual tumor growth is seen. In this study, the authors evaluated the efficacy of this multimodality approach, particularly the influence of timing and dose of SRS on radiological tumor control, need for salvage treatment, and cranial nerve function.
VS patients treated with initial microsurgery and subsequent radiosurgery were retrospectively included from two tertiary treatment centers and dichotomized depending on whether SRS was given upfront (defined as before 12 months) or later. Radiological tumor control was defined as less than 20% tumor volume expansion and oncological tumor control as an absence of salvage treatment. Facial and cochlear nerve functions were assessed after surgery, at the time of SRS, and at last follow-up. Finally, a systematic literature review was conducted according to PRISMA guidelines.
A total of 110 VS patients underwent SRS following microsurgical resection, with a mean preradiosurgical tumor volume of 2.2 cm3 (SD 2.5 cm3) and mean post-SRS follow-up time of 5.8 years (SD 4.1 years). The overall radiological tumor control and oncological tumor control were 77.3% and 90.9%, respectively. Thirty-five patients (31.8%) received upfront SRS, while 75 patients (68.2%) were observed for a minimum of 12 months prior to SRS. The timing of SRS did not influence the radiological tumor control (p = 0.869), the oncological tumor control (p = 0.560), or facial nerve (p = 0.413) or cochlear nerve (p = 0.954) function. An escalated marginal dose (> 12 Gy) was associated with greater tumor shrinkage (p = 0.020) and superior radiological tumor control (p = 0.020), but it did not influence the risk of salvage treatment (p = 0.904) or facial (p = 0.351) or cochlear (p = 0.601) nerve deterioration.
Delayed SRS after close observation of residuals following STR is a safe alternative to upfront SRS regarding tumor control and cranial nerve preservation in selected patients.
前庭神经鞘瘤（VS）显微手术切除的目标是实现肿瘤全切除（GTR）以达到肿瘤学治愈。然而，一种常用策略是，如果手术团队认为即将发生颅神经损伤风险，则停止切除，转而实现最大程度安全的次全切除（STR）。一旦患者从术后急性期恢复，肿瘤残余可接受立体定向放射外科治疗（SRS），或者对其进行系列影像学检查，若发现残余肿瘤生长，则延迟进行SRS治疗。在本研究中，作者评估了这种多模式治疗方法的疗效，尤其是SRS的时机和剂量对肿瘤放射学控制、挽救性治疗需求以及颅神经功能的影响。
回顾性纳入来自两个三级治疗中心接受初始显微手术及后续放射外科治疗的VS患者，并根据SRS是在早期（定义为12个月之前）还是晚期进行给予进行二分法分类。肿瘤放射学控制定义为肿瘤体积扩大小于20%，肿瘤学控制定义为无需挽救性治疗。在术后、SRS时以及末次随访时评估面神经和听神经功能。最后，根据PRISMA指南进行系统的文献综述。
共有110例VS患者在显微手术切除后接受了SRS，放射外科治疗前肿瘤平均体积为2.2 cm³（标准差2.5 cm³），SRS后平均随访时间为5.8年（标准差4.1年）。总体肿瘤放射学控制率和肿瘤学控制率分别为77.3%和90.9%。35例患者（31.8%）接受了早期SRS，而75例患者（68.2%）在SRS前至少观察了12个月。SRS的时机不影响肿瘤放射学控制（p = 0.869）、肿瘤学控制（p = 0.560）、面神经（p = 0.413）或听神经（p = 0.954）功能。增加边缘剂量（> 12 Gy）与更大程度的肿瘤缩小（p = 0.020）和更好的肿瘤放射学控制（p = 0.020）相关，但不影响挽救性治疗风险（p = 0.904）或面神经（p = 0.351）或听神经（p = 0.601）恶化情况。
对于部分患者，在STR后密切观察残余肿瘤后延迟进行SRS在肿瘤控制和颅神经保留方面是早期SRS的一种安全替代方案。
