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BioMed Research International
Volume 2013 (2013), Article ID 297093, 6 pages
http://dx.doi.org/10.1155/2013/297093
Clinical Study

Clinical Evaluation of CyberKnife in the Treatment of Vestibular Schwannomas

1Department of Radiation-Oncology, Taipei Medical University Wan-Fang Hospital, Taipei 110, Taiwan
2Department of Radiation-Oncology, Taipei Medical University Shuang-Ho Hospital, New Taipei City 23561, Taiwan
3Department of Neurosurgery, Taipei Medical University Wan-Fang Hospital, Taipei 110, Taiwan
4Department of Neurosurgery, Taipei Medical University Shuang-Ho Hospital, New Taipei City 23561, Taiwan
5Department of Neurological Surgery, Tri-Service General Hospital, National Defense Medical Center, No. 325, Section 2, Chenggong Road, Neihu District, Taipei 114, Taiwan
6Department of Radiation Oncology, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan
7Stereotactic Radiosurgery Center, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan

Received 9 May 2013; Revised 27 September 2013; Accepted 1 October 2013

Academic Editor: Sonshin Takao

Copyright © 2013 Jo-Ting Tsai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. This study assessed the posttreatment tumor control and auditory function of vestibular schwannoma (VS) patients after CyberKnife (CK) and analyzed the possible prognostic factors of hearing loss. Methods. We retrospectively studied 117 VS patients, with Gardner-Robertson (GR) classification grades I to IV, who underwent CK between 2006 and 2012. Data including radiosurgery treatment parameters, pre- and postoperative tumor size, and auditory function were collected and examined. Results. With CK, 117 patients had excellent tumor control rates (99.1%), with a mean imaging followup of 61.1 months. Excluding 52 patients (GR III-IV pretreatment), 53 (81.5%) of the remaining 65 patients (initial GR I-II) maintained GR I or II hearing after CK, with a mean audiometric followup of 64.5 months. Twelve patients experienced hearing degradation (91.6% were GR II pretreatment); they appeared to have significantly larger tumor sizes, significantly smaller cochlear sizes, and higher prescribed cochlear doses, compared to the patients with preserved hearing. Conclusion. Our data showed that CK treatment provided an excellent tumor control rate and a comparable hearing preservation rate in VS patients. Patients with pretreatment GR II hearing levels, larger tumor volumes, smaller cochlear sizes, and higher prescribed cochlear doses may have poor hearing prognoses.