In:
Journal of Neurosurgery, Journal of Neurosurgery Publishing Group (JNSPG), ( 2022-09-01), p. 1-8
Abstract:
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. METHODS 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. RESULTS 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 cm 3 (range 0.12–18.77 cm 3 ) 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. CONCLUSIONS 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.
Type of Medium:
Online Resource
ISSN:
0022-3085
,
1933-0693
DOI:
10.3171/2022.7.JNS22812
Language:
Unknown
Publisher:
Journal of Neurosurgery Publishing Group (JNSPG)
Publication Date:
2022
detail.hit.zdb_id:
2026156-1
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