Long-term follow-up results of linear accelerator-based radiosurgery for vestibular schwannoma using serial three-dimensional spoiled gradient-echo MRI.

Abstract

We examined the characteristic changes in vestibular schwannoma (VS) volume after treatment with linear accelerator-based radiosurgery (LBRS) and the long-term therapeutic effects, by performing three-dimensional (3D) MRI evaluations of tumor volumes. We included 44 patients in whom tumor volume changes could be observed using 3D-spoiled gradient-echo MRI for at least 5 years. Examinations were performed every 3-4 months for the first 2 years after treatment and every 6-12 months thereafter. Enlargement or shrinkage was determined as a change of at least 20% from the volume at the time of treatment. The median observation period was 13.8 years (range, 5.5-19.5 years). The tumor control rates at 5 and 10 years after treatment and at the final MRI were 90.9%, 90.0%, and 88.6%, respectively. Tumor volume changes were categorized into the following four patterns: enlargement, five patients (11.4%); stable, three patients (6.8%); transient enlargement, 24 patients (54.5%); and direct shrinkage, 12 patients (27.3%). Bimodal peaks were observed in three of the 24 patients with transient enlargement. Tumor volume changes from 5 and 10 years post-LBRS to the final observation point were observed in 27 (64.2%) and 10 patients (33.3%), respectively. The long-term tumor volume changes observed after LBRS suggest that radiation exerts long-term effects on tumors. Furthermore, while transient enlargements in tumor volume were characteristic, true tumor enlargements should be characterized by increased volumes of more than two-fold and continued growth for at least 2 years.

• Authors: Takayuki Matsuo, Tomohiro Okunaga, Kensaku Kamada, Tsuyoshi Izumo, Nobuyuki Hayashi, Izumi Nagata
• Journal: Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia (J Clin Neurosci) Vol. 22 Issue 2 Pg. 320-5 (Feb 2015) ISSN: 1532-2653 [Electronic] Scotland
• PMID: 25443082 (Publication Type: Journal Article)
• Copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.

Topics

• Adult
• Aged
• Female
• Follow-Up Studies
• Humans
• Imaging, Three-Dimensional (methods)
• Magnetic Resonance Imaging (methods)
• Male
• Middle Aged
• Neuroma, Acoustic (pathology, surgery)
• Particle Accelerators
• Radiosurgery (methods)
• Tumor Burden