Gamma Knife surgery of large meningiomas: early response to treatment

Ganz, Jeremy C.; Reda, Wael A; Abdelkarim, Khaled

doi:10.1007/s00701-008-0166-4

Cited by 46 publications

(36 citation statements)

References 51 publications

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“…29 Other studies, including one from the University of Pittsburgh, have found that tumor volume greater than 8 cm 3 was the most important parameter associated with a worse prognosis for radiosurgery of benign meningiomas. 8,15,16,20 From 1989 through 2012, our Gamma Knife center treated 75 patients with meningiomas at least 8 cm 3 in volume at initial planning (mean preradiosurgical tumor volume = 14.1 cm 3 ). Forty percent of patients were treated with primary radiosurgery, and the remaining 60% were treated following resection.…”

Section: Discussionmentioning

confidence: 99%

“…[30][31][32] In prior studies, large meningiomas have been treated with varying degrees of success, but radiosurgery outcomes appear to worsen for patients harboring meningiomas greater than 8 cm 3 in volume. 8,15,16,20,42 An 8-cm 3 volume corresponds to a lesion with an approximate diameter of 2.5 cm. Radiosurgery to lesions in excess of 8-cm 3 volume has been linked to worsening outcome with arteriovenous malformations, acoustic neuromas, and brain metastases as well.…”

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confidence: 99%

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Gamma Knife radiosurgery of large skull base meningiomas

Starke¹,

Przybylowski²,

Mukherjee

et al. 2015

JNS

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M eningioMas are the most frequently reported primary intracranial neoplasms in the US. Most of these lesions are benign (i.e., WHO Grade I) with a low tendency for invasion and recurrence and a natural history of slow growth. Within the intracranial space, there is a narrow capacity for mass expansion. The primary approach for large meningiomas has been resection. Despite a dramatic decline in surgical morbidity for abbreviatioNs CN = cranial nerve; CPA = cerebellopontine angle; GKRS = Gamma Knife radiosurgery; HR = hazard ratio; SRS = stereotactic radiosurgery. submitted January 26, 2014. accepted October 14, 2014. iNclude wheN citiNg Published online December 5, 2014; DOI: 10.3171/2014.10.JNS14198. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. obJect Stereotactic radiosurgery (SRS) has become a common treatment modality for intracranial meningiomas. Skull base meningiomas greater than 8 cm 3 in volume have been found to have worse outcomes following SRS. When symptomatic, patients with these tumors are often initially treated with resection. For tumors located in close proximity to eloquent structures or in patients unwilling or unable to undergo a resection, SRS may be an acceptable therapeutic approach. In this study, the authors review the SRS outcomes of skull base meningiomas greater than 8 cm 3 in volume, which corresponds to a lesion with an approximate diameter of 2.5 cm. methods The authors reviewed the data in a prospectively compiled database documenting the outcomes of 469 patients with skull base meningiomas treated with single-session Gamma Knife radiosurgery (GKRS). Seventy-five patients had tumors greater than 8 cm 3 in volume, which was defined as a large tumor. All patients had a minimum follow-up of 6 months, but patients were included if they had a complication at any time point. Thirty patients were treated with upfront GKRS, and 45 were treated following microsurgery. Patient and tumor characteristics were assessed to determine predictors of new or worsening neurological function and tumor progression following GKRS. results After a mean follow-up of 6.5 years (range 0.5-21 years), the tumor volume was unchanged in 37 patients (49%), decreased in 26 patients (35%), and increased in 12 patients (16%). Actuarial rates of progression-free survival at 3, 5, and 10 years were 90.3%, 88.6%, and 77.2%, respectively. Four patients had new or worsened edema following GKRS, but preexisting edema decreased in 3 patients. In Cox multivariable analysis, covariates associated with tumor progression were 1) presentation with any cranial nerve (CN) deficit from III to VI (hazard ratio [HR] 3.78, 95% CI 1.91-7.45; p < 0.001), history of radiotherapy (HR 12.06, 95% CI 2.04-71.27; p = 0.006), and tumor volume greater than 14 cm 3 (HR 6.86, p = 0.066). In those patients with detailed clinical follow-up (n = 64), neurological function was unchanged in 37 patients (58%), improved in 16 patients (25%), and d...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Gamma Knife radiosurgery of large skull base meningiomas

Starke¹,

Przybylowski²,

Mukherjee

et al. 2015

JNS

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“…According to the literature, radiosurgical treatments for large‐volume tumors or AVMs may sustain a higher risk of complications, such as tumor swelling or brain edema 1, 2, 3, 10, 13. Ideally, a conformal and sufficient target dose should be maintained for effective treatment.…”

Section: Discussionmentioning

confidence: 99%

“…Over the last decade, an increasing number of studies have shown that large intracranial lesions with a volume of 20–30 cm 3 can also be treated using GKRS 1, 2, 3, 4. Typically, multiple shots are required to cover target volumes (TVs) for treating large targets.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, multiple shots are also used for targets with irregular contours to achieve improved target conformity. However, large or irregularly shaped targets are at an increased risk of radiation‐induced complications because more normal tissues inside or surrounding the targets are irradiated 1, 2, 3, 4. Ideally, the maximum treatment dose should be decreased to reduce the risk of complications, while concurrently maintaining a sufficiently high target dose 1, 5.…”

Section: Introductionmentioning

confidence: 99%

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Forward treatment planning techniques to reduce the normalization effect in Gamma Knife radiosurgery

Cheng

Kuo

et al. 2017

J Applied Clin Med Phys

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In Gamma Knife forward treatment planning, normalization effect may be observed when multiple shots are used for treating large lesions. This effect can reduce the proportion of coverage of high‐value isodose lines within targets. The aim of this study was to evaluate the performance of forward treatment planning techniques using the Leksell Gamma Knife for the normalization effect reduction. We adjusted the shot positions and weightings to optimize the dose distribution and reduce the overlap of high‐value isodose lines from each shot, thereby mitigating the normalization effect during treatment planning. The new collimation system, Leksell Gamma Knife Perfexion, which contains eight movable sectors, provides an additional means to reduce the normalization effect by using composite shots. We propose different techniques in forward treatment planning that can reduce the normalization effect. Reducing the normalization effect increases the coverage proportion of higher isodose lines within targets, making the high‐dose region within targets more uniform and increasing the mean dose to targets. Because of the increase in the mean dose to the target after reducing the normalization effect, we can set the prescribed marginal dose at a higher isodose level and reduce the maximum dose, thereby lowering the risk of complications.

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