Patterns of Tumor Response and Nonauditory Morbidity Following Contemporary Reduced Dose Gamma Knife Radiosurgery for Vestibular Schwannoma

OBJECTIVE Gamma Knife radiosurgery (GKRS) is a common treatment modality for vestibular schwannoma (VS). The ability to predict treatment response is important in patient counseling and decision-making. The authors developed an algorithm that can automatically segment and differentiate cystic and solid tumor components of VS. They also investigated associations between the quantified radiological features of each component and tumor response after GKRS. METHODS This is a retrospective study comprising 323 patients with VS treated with GKRS. After preprocessing and generation of pretreatment T2-weighted (T2W)/T1-weighted with contrast (T1WC) images, the authors segmented VSs into cystic and solid components by using fuzzy C-means clustering. Quantitative radiological features of the entire tumor and its cystic and solid components were extracted. Linear regression models were implemented to correlate clinical variables and radiological features with the specific growth rate (SGR) of VS after GKRS. RESULTS A multivariable linear regression model of radiological features of the entire tumor demonstrated that a higher tumor mean signal intensity (SI) on T2W/T1WC images (p < 0.001) was associated with a lower SGR after GKRS. Similarly, a multivariable linear regression model using radiological features of cystic and solid tumor components demonstrated that a higher solid component mean SI (p = 0.039) and a higher cystic component mean SI (p = 0.004) on T2W/T1WC images were associated with a lower SGR after GKRS. A larger cystic component proportion (p = 0.085) was associated with a trend toward a lower SGR after GKRS. CONCLUSIONS Radiological features of VSs on pretreatment MRI that were quantified using fuzzy C-means were associated with tumor response after GKRS. Tumors with a higher tumor mean SI, a higher solid component mean SI, and a higher cystic component mean SI on T2W/T1WC images were more likely to regress in volume after GKRS. Those with a larger cystic component proportion also trended toward regression after GKRS. Further refinement of the algorithm may allow direct prediction of tumor response.

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Risk factors and tumor response associated with hydrocephalus after gamma knife radiosurgery for vestibular schwannoma

Acta Neurochirurgica ◽

10.1007/s00701-012-1350-0 ◽

2012 ◽

Vol 154 (9) ◽

pp. 1679-1684 ◽

Cited By ~ 11

Author(s):

Seung Hoon Lee ◽

Ho Jun Seol ◽

Doo Sik Kong ◽

Do-Hyun Nam ◽

Kwan Park ◽

...

Keyword(s):

Risk Factors ◽

Gamma Knife ◽

Vestibular Schwannoma ◽

Tumor Response ◽

Gamma Knife Radiosurgery

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Gamma Knife Radiosurgery does not alter the copy number aberration profile in sporadic vestibular schwannoma

Journal of Neuro-Oncology ◽

10.1007/s11060-020-03631-4 ◽

2020 ◽

Vol 149 (3) ◽

pp. 373-381

Author(s):

Aril Løge Håvik ◽

Ove Bruland ◽

Dhanushan Dhayalan ◽

Morten Lund-Johansen ◽

Per-Morten Knappskog

Keyword(s):

Radiation Exposure ◽

Gamma Knife ◽

Vestibular Schwannoma ◽

Copy Number ◽

Statistical Tests ◽

Gamma Knife Radiosurgery ◽

Copy Number Aberration ◽

Recurrent Event ◽

Chromosome 22 ◽

Increased Risk

Abstract Introduction Ionizing radiation is a known etiologic factor in tumorigenesis and its role in inducing malignancy in the treatment of vestibular schwannoma has been debated. The purpose of this study was to identify a copy number aberration (CNA) profile or specific CNAs associated with radiation exposure which could either implicate an increased risk of malignancy or elucidate a mechanism of treatment resistance. Methods 55 sporadic VS, including 18 treated with Gamma Knife Radiosurgery (GKRS), were subjected to DNA whole-genome microarray and/or whole-exome sequencing. CNAs were called and statistical tests were performed to identify any association with radiation exposure. Hierarchical clustering was used to identify CNA profiles associated with radiation exposure. Results A median of 7 (0–58) CNAs were identified across the 55 VS. Chromosome 22 aberration was the only recurrent event. A median aberrant cell fraction of 0.59 (0.25–0.94) was observed, indicating several genetic clones in VS. No CNA or CNA profile was associated with GKRS. Conclusion GKRS is not associated with an increase in CNAs or alteration of the CNA profile in VS, lending support to its low risk. This also implies that there is no major issue with GKRS treatment failure being due to CNAs. In agreement with previous studies, chromosome 22 aberration is the only recurrent CNA. VS consist of several genetic clones, addressing the need for further studies on the composition of cells in this tumor.

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