Albano Luigi, Deng Hansen, Wei Zhishuo, Vodovotz Lena, Niranjan Ajay, Lunsford L Dade
1Department of Neurological Surgery and.
2Center for Image-Guided Neurosurgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
J Neurosurg. 2022 Sep 9;138(5):1273-1280. doi: 10.3171/2022.7.JNS22812. Print 2023 May 1.
Gamma Knife radiosurgery (GKRS) is an effective treatment for vestibular schwannomas (VSs) and has been used in > 100,000 cases worldwide. In the present study the authors sought to define the serial volumetric tumor response of Koos grade I-IV VS after radiosurgery.
A total of 201 consecutive VS patients underwent GKRS at a single institution between 2015 and 2019. All patients had a minimum follow-up of 18 months and at least 2 interval postprocedure MRI scans. The contrast-enhanced tumor volumes were contoured manually and compared between pre- and post-GKRS imaging. The percentages of tumor volume change at 18 months (short-term follow-up) and up to 5 years after GKRS (long-term follow-up) were compared with the baseline tumor volume. An increase of 20% was considered a significant increase of tumor volume. Trends of tumor volume over time were assessed with linear models using time as a continuous variable. A test for linear trend was evaluated according to the initial Koos tumor classification.
Koos grade II VS was the most frequently occurring tumor (n = 74, 36.8%), followed by grade III (n = 57, 28.4%), grade I (n = 41, 20.4%), and grade IV (n = 29, 14.4%). The mean tumor volume at the time of GKRS was 2.12 ± 2.82 cm3 (range 0.12-18.77 cm3) and the median margin dose was 12 Gy. Short-term follow-up revealed that tumor volumes transiently increased in 34.2% and 28.4% of patients at 6 and 18 months, respectively, regardless of Koos grade. Linear regression analysis of Koos grade II, III, and IV tumors showed a significant longitudinal volume decrease on long-term follow-up. At last follow-up (median 30 months, range 18-54 months), 19 patients (9.4%) showed a persistent increase of tumor volume. Five patients received additional management after GKRS.
Although selected VS patients demonstrate an early and measurable transient volumetric increase after GKRS, > 90% have stable or reduced tumor volumes over an observed period of up to 5 years. Volumetric regression is most pronounced in Koos grade II, III, and IV tumors and may not be fully detectable until 3 years after GKRS.
伽玛刀放射外科治疗（GKRS）是治疗前庭神经鞘瘤（VS）的一种有效方法，已在全球应用于超过100,000例患者。在本研究中，作者试图明确放射外科治疗后Koos I-IV级VS的肿瘤体积的连续变化情况。
2015年至2019年间，共有201例连续的VS患者在单一机构接受了GKRS治疗。所有患者的最短随访时间为18个月，且术后至少进行了2次间隔的MRI扫描。手动勾勒出增强扫描的肿瘤体积，并在GKRS治疗前后的影像学检查之间进行比较。将GKRS治疗后18个月（短期随访）和长达5年（长期随访）时的肿瘤体积变化百分比与基线肿瘤体积进行比较。肿瘤体积增加20%被认为是肿瘤体积的显著增加。使用时间作为连续变量的线性模型评估肿瘤体积随时间的变化趋势。根据初始的Koos肿瘤分类评估线性趋势检验。
Koos II级VS是最常见的肿瘤（n = 74，36.8%），其次是III级（n = 57，28.4%）、I级（n = 41，20.4%）和IV级（n = 29，14.4%）。GKRS治疗时的平均肿瘤体积为2.12±2.82 cm³（范围0.12 - 18.77 cm³），中位边缘剂量为12 Gy。短期随访显示，无论Koos分级如何，分别有34.2%和28.4%的患者在6个月和18个月时肿瘤体积短暂增加。对Koos II级、III级和IV级肿瘤的线性回归分析显示，长期随访时肿瘤体积有显著的纵向减小。在最后一次随访时（中位时间30个月，范围18 - 54个月），19例患者（9.4%）的肿瘤体积持续增加。5例患者在GKRS治疗后接受了额外的治疗。
尽管部分VS患者在GKRS治疗后早期出现可测量的短暂体积增加，但在长达5年的观察期内，超过90%的患者肿瘤体积稳定或减小。体积缩小在Koos II级、III级和IV级肿瘤中最为明显，可能在GKRS治疗后3年才完全显现。
