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30-06-2011 | Surgery | Article

Gamma Knife surgery ‘durable’ option for parasellar meningiomas

Abstract

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MedWire News: Gamma Knife surgery provides good control of parasellar meningiomas, particularly small-volume tumors, and is associated with a low complication rate, say researchers.

"Larger-volume tumors, however, may benefit from a cytoreductive resection prior to radiosurgery," say Jason Sheehan (University of Virginia Health System, Charlottesville, USA) and co-workers.

The team reviewed long-term outcomes of 138 patients (107 women, 31 men), aged between 19 and 85 years, who received treatment for parasellar meningiomas at the University of Virginia between 1989 and 2006.

All patients had at least 2 years of follow-up, with an average of 84 months.

Outcomes were generally good, with 86% of patients having an unchanged (52 patients) or decreased (66 patients) tumor volume at their most recent assessment.

Radiographic progression-free survival was 95% at 5 years, 86% and 7 years, and 69% at 10 years.

Twenty patients had increases in the volumes of their tumors during follow-up. Sheehan et al note that follow-up was shorter in patients with unchanged tumor volumes than in those with decreased or increased tumor volumes, at 73.9, 86.2, and 102.8 months, respectively.

Patients with unchanged or decreased tumor volumes were younger than those whose tumors increased in size, and had smaller baseline tumor volumes and higher maximum isodoses. On multivariate analysis, only younger age remained associated with tumor control.

Gamma Knife surgery produced a low incidence of complications, the team reports in the Journal of Neurosurgery.

New cranial nerve deficits, or worsening of existing ones, occurred in 10% of patients after treatment. These included four optic neuropathies, three oculomotor nerve palsies, and six trigeminal nerve deficits.

But Sheehan et al note: "The vast majority of patients in our series who had new or worsened cranial nerve deficits appeared to develop them not in response to radiation-induced injury, but due to tumor progression."

Indeed, 79% of patients with new or worsening nerve deficits had tumor progression, and this was the only factor associated with nerve deficits on multivariate analysis.

In an accompanying editorial, Fredric Meyer (Mayo Clinic, Rochester, Minnesota, USA) cautioned: "The surgeon and radiation therapist need to be thoughtful as to the timing of radiosurgical intervention."

He explained: "The natural history and growth rate of these tumors are often very benign. It is not unreasonable to observe asymptomatic tumors with 9-12-month interval [magnetic resonance] imaging and only intervene when there is evidence of progression."

Meyer concluded: "Hence, even this fine publication presents good but not absolute evidence, because there is no prospective untreated group for comparison."

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Eleanor McDermid

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