Tag: tumor control

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Long-term tumor control after Gamma Knife radiosurgery for sporadic vestibular schwannoma

J Neurosurg 144:965–971, 2026

This clinical study evaluates long-term tumor control after single-fraction Gamma Knife stereotactic radiosurgery (SRS) for sporadic vestibular schwannoma in 749 adults treated from 2000–2022, reporting Kaplan–Meier control rates of 100%, 98%, 96%, 92%, and 91% at 1, 3, 5, 10, and 15 years respectively. Patient demographics, SRS dosing, and complication rates—including low persistent facial paresis—are summarized with statistical analysis and clear definitions for growth, pseudoprogression, and salvage.

The authors detail three post-SRS tumor behavior patterns, finding 13% pseudoprogression (mostly within 5 years) and 42 salvage treatments (median 3.7 years), and conclude that SRS offers durable control while emphasizing the need for prolonged surveillance and nuanced clinical decision-making about retreatment.

Objective Assess long-term efficacy of single-fraction stereotactic radiosurgery (SRS) as primary treatment for adult, treatment-naïve sporadic vestibular schwannoma (Gamma Knife), treated from 2000–2022.

Cohort 749 adults included; 76% had tumors extending into the cerebellopontine angle (CPA) at SRS; median age 62; 50% women; 99% had House-Brackmann (HB) grade I facial nerve function at SRS.

Long-term tumor control Tumor control after SRS remained high: 100% (1 yr), 98% (3 yr), 96% (5 yr), 92% (10 yr), and 91% (15 yr).

Radiosurgical failure/salvage 42 patients required salvage (35 microsurgery, 7 repeat SRS), median 3.7 years post-SRS; 3 salvage treatments occurred >10 years after SRS, indicating late failures can occur.

Risk factors Age, macrocystic tumor presence, and treated tumor volume were not significantly associated with risk of salvage in univariable analysis.

Post-SRS tumor patterns Three post-SRS behaviors were observed: (1) stability/shrinkage, (2) pseudoprogression (growth then stability/shrinkage), and (3) continued growth without stability at last follow-up.

Pseudoprogression timing 13% experienced pseudoprogression; all but 4 showed it by year 5 post-SRS, though some initial growth occurred later (e.g., 5.1–8.6 years) with subsequent stability on follow-up imaging.

Conclusion/implication SRS provides durable control through 15 years for most patients (91%), but ongoing long-term surveillance is needed because failures may occur even beyond 10 years and pseudoprogression can be seen out to ≥5 years.

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The longitudinal volumetric response of vestibular schwannomas after Gamma Knife radiosurgery

J Neurosurg 138:1273–1280, 2023

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.

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A Prospective Cohort Study of Neural Progenitor Cell-Sparing Radiation Therapy Plus Temozolomide for Newly Diagnosed PatientsWith Glioblastoma

Neurosurgery 87:E31–E40, 2020

In treating glioblastoma, irradiation of the neural progenitor cell (NPC) niches is controversial. Lower hippocampal doses may limit neurocognitive toxicity, but higher doses to the subventricular zones (SVZ) may improve survival.

OBJECTIVE: To prospectively evaluate the impact of limiting radiation dose to the NPC niches on tumor progression, survival, and cognition in patients with glioblastoma.

METHODS: Patients with glioblastoma received resection followed by standard chemoradiation. Radiation dose to the NPC niches, including the bilateral hippocampi and SVZ, was minimized without compromising tumor coverage. The primary outcome was tumor progression in the spared NPC niches. Follow-up magnetic resonance imaging was obtained bimonthly. Neurocognitive testing was performed before treatment and at 6- and 12-mo follow-up. Cox regression evaluated predictors of overall and progressionfree survival. Linear regression evaluated predictors of neurocognitive decline. RESULTS: A total of 30 patients enrolled prospectively. The median age was 58 yr. Median mean doses to the hippocampi and SVZ were 49.1 and 41.8 gray (Gy) ipsilaterally, and 16.5 and 19.9 Gy contralaterally. Median times to death and tumor progression were 16.0 and 7.6 mo, and were not significantly different compared to a matched historical control. No patients experienced tumor progression in the spared NPC-containing regions. Overall survival was associated with neurocognitive function (P ≤ .03) but not dose to the NPC niches. Higher doses to the hippocampi and SVZ predicted greater decline in verbal memory (P ≤ .01).

CONCLUSION: In treating glioblastoma, limiting dose to the NPC niches may reduce cognitive toxicity while maintaining clinical outcomes. Further studies are needed to confirm these results.

 

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Control of vestibular schwannomas treated with Gamma Knife

vestibular-schwannoma

J Neurosurg 124:1619–1626, 2016

The authors of this study sought to assess tumor control and complication rates in a large cohort of patients who underwent Gamma Knife radiosurgery (GKRS) for vestibular schwannoma (VS) and to identify predictors of tumor control. Methods The records of 420 patients treated with GKRS for VS with a median marginal dose of 11 Gy were retrospectively analyzed. Patients with neurofibromatosis Type 2 or who had undergone treatment for VS previously were excluded. The authors assessed tumor control and complication rates with chart review and used the Cox proportional hazards model to identify predictors of tumor control. Preservation of serviceable hearing, defined as Gardner-Robertson Class I–II, was evaluated in a subgroup of 71 patients with serviceable hearing at baseline and with available followup audiograms.

Results The median VS tumor volume was 1.4 cm3, and the median length of follow-up was 5.1 years. Actuarial 5- and 10-year tumor control rates were 91.3% and 84.8%, respectively. Only tumor volume was a statistically significant predictor of tumor control rate. The tumor control rate decreased from 94.1% for tumors smaller than 0.5 cm3 to 80.7% for tumors larger than 6 cm3. Thirteen patients (3.1%) had new or increased permanent trigeminal nerve neuropathy, 4 (1.0%) had new or increased permanent facial weakness, and 5 (1.2%) exhibited new or increased hydrocephalus requiring a shunting procedure. Actuarial 3-year and 5-year hearing preservation rates were 65% and 42%, respectively.

Conclusions The 5-year actuarial tumor control rate of 91.3% in this cohort of patients with VS compared slightly unfavorably with the rates reported in other large studies, but the complication and hearing preservation rates in this study were similar to those reported previously. Various factors may contribute to the observed differences in reported outcomes. These factors include variations in treatment indication and in the definition of treatment failure, as well as a lack of standardization of terminology and of evaluation of complications. Last, differences in dosimetric variables may also be an explanatory factor.

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Jugulotympanic paragangliomas treated with Gamma Knife radiosurgery

Jugulotympanic paragangliomas treated with Gamma Knife radiosurgery- a single-center review of 58 cases

J Neurosurg 121:1158–1165, 2014

Jugulotympanic paragangliomas (JTPs) are rare benign tumors whose surgical treatment is usually associated with partial resection of the lesion, high morbidity, and even death. Gamma Knife radiosurgery (GKRS) has been reported as a useful treatment option. The goal of this retrospective study is to analyze the role of GKRS in tumor volume control and clinical outcomes of these patients.

Methods. A total of 75 patients with JTPs were treated with GKRS at the authors’ center from 1995 to 2012. The authors analyzed those treated during this period to allow for a minimal observation time of 2 years. The MR images and clinical reports of these patients were reviewed to assess clinical and volumetric outcomes of the tumors. The radiological and clinical assessments, along with a group of prognostic factors measured, were analyzed using descriptive methods. The time to volumetric and clinical progression was analyzed using the Kaplan-Meier method. Prognostic factors were identified using log-rank statistics and multivariate Cox regression models.

Results. The mean follow-up was 86.4 months. The authors observed volumetric tumor control in 94.8% of cases. In 67.2% of cases, tumor volume decreased by a mean of 40.1% from the original size. Of patients with previous tinnitus, 54% reported complete recovery. Improvement of other symptoms was observed in 34.5% of cases. Overall, clinical control was achieved in 91.4% of cases. Previous embolization and familial history of paraganglioma were selected as significant prognostic factors for volumetric response to GKRS treatment in the univariate analysis. In multivariate analysis, no factors were significantly correlated with progression-free survival. No patient died of side effects related to GKRS treatment or tumor progression.

Conclusions. Gamma Knife radiosurgery is an effective, safe, and efficient therapeutic option for the treatment of these tumors as a first-line treatment or in conjunction with traditional surgery, endovascular treatment, or conventional fractionated radiotherapy.

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