SBRT of vestibular schwannomas Stereotactic radiation therapy for large vestibular schwannomas Ellen S. Mandl a, * , Otto W.M. Meijer b , Ben J. Slotman b , W. Peter Vandertop a , Saskia M. Peerdeman a a Neurosurgical Center Amsterdam; and b Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands article info Article history: Received 24 February 2009 Received in revised form 18 December 2009 Accepted 29 December 2009 Keywords: Vestibular schwannoma Radiosurgery Radiotherapy Complication abstract Background and purpose: To evaluate the morbidity and tumor-control rate in the treatment of large ves- tibular schwannomas (VS) after stereotactic radiation therapy in our institution. Material and methods: Twenty-five consecutive patients (17 men, 8 women) with large VS (diameter 3.0 cm or larger), treated with stereotactic radiotherapy (SRT) or stereotactic radiosurgery (SRS) between 1992 and 2007, were retrospectively studied after a mean follow-up period of three years with respect to tumor-control rate and complications. Results: Actuarial 5-year maintenance of pre-treatment hearing level probability of 30% was achieved. Five of 17 patients suffered permanent new facial nerve dysfunction. The actuarial 5-year facial nerve preservation probability was 80%. Permanent new trigeminal nerve neuropathy occurred in two of 15 patients, resulting in an actuarial 5-year trigeminal nerve preservation probability of 85%. Tumor pro- gression occurred in four of 25 (16%) patients. The overall 5-year tumor control probability was 82%. Conclusion: Increased morbidity rates were found in patients with large VS treated with SRT or SRS compared to the published series on regular sized VS and other smaller retrospective studies on large VS. Ó 2010 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 95 (2010) 94–98 Treatment strategies for vestibular schwannomas (VS) consist of microsurgical resection, stereotactic radiotherapy (SRT) or radiosurgery (SRS), watchful waiting or a combination of these modalities [1–5]. In our institution, low morbidity and good local tumor-control rates were achieved for small to medium-sized VS treated with SRT or SRS [6,7]. In large VS (diameter 3.0 cm or larger), microsurgical resection is considered to be the standard treatment in order to effectively obvi- ate the compression of structures surrounding the tumor like the facial and trigeminal nerves, the cerebellum, and the brainstem [8,9]. With increasing tumor size the percentage of functional nerve preservation decreases and surgical complications increase. For large VS, facial nerve preservation rates range from 45% to 78% and surgical complications like meningitis and cerebrospinal fluid (CSF) fistula become as high as 28% [5,10,11]. Recently, gamma knife surgery of the selected large VS was described as an alterna- tive treatment [2,12,13], as was fractionated SRT using a linear accelerator (LINAC) [8,14]. Possible benefits of SRT and SRS com- pared to microsurgical resection in large VS are hearing preserva- tion and a lower incidence of trigeminal and facial nerve palsies. We retrospectively analyzed the morbidity and tumor-control rates in patients treated for large VS with SRT or SRS at our institution and these data are presented in relation to the published series. Patients and methods Patients From January 1992 to March 2007 a total of 276 consecutive pa- tients with VS were treated with SRT or SRS at the VU University medical center, Amsterdam (the Netherlands). Patients with VS tu- mor diameter of 3.0 cm or larger on magnetic resonance (MR) imaging in either one of three planes (axial, sagittal and coronal) were used for this study. In total, 29 patients with large VS were identified. Tumor diameter was measured on pre-treatment MR- images by a diagnostic radiologist at the time of the actual scan. The medical records of all eligible patients were studied with re- spect to: initial symptoms at presentation, treatment modality (SRT or SRS), microsurgical procedures before and after radiation therapy and duration of clinical follow-up. The need for an addi- tional steroid treatment, the development of hydrocephalus with or without the need for cerebrospinal fluid (CSF) shunting, radio- logical signs of radiation necrosis, and the development of trigem- inal, facial or other cranial neuropathies after treatment was also recorded. Because of the retrospective nature of this study, reliable use of the House–Brackman, and the Gardner–Robertson grading scale could not be made. All adverse events, temporary or perma- nent, were registered to emphasize true patient morbidity related to treatment. Local tumor control was defined as stable (no increase in tumor diameter with the inclusion of a maximum measurement error of 0.2 cm) or decreased maximum tumor diameter on follow-up MR-imaging. Symptomatic tumor necrosis 0167-8140/$ - see front matter Ó 2010 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.radonc.2009.12.042 * Corresponding author. Address: Department of Neurosurgery, 1F-002, VU University Medical Center, P.O. Box 7057, 1007 MB Amsterdam, The Netherlands. E-mail address: es.mandl@vumc.nl (E.S. Mandl). Radiotherapy and Oncology 95 (2010) 94–98 Contents lists available at ScienceDirect Radiotherapy and Oncology journal homepage: www.thegreenjournal.com