CyberKnife for Treatment of Vestibular Schwannoma: A Meta‐analysis

Abstract

Objectives. (1) Perform a meta-analysis of the available data on the outcomes of CyberKnife radiosurgery for treatment of vestibular schwannomas (VSs) in the published English-language literature and (2) evaluate the collective outcomes of CyberKnife treatment with respect to tumor control and hearing preservation. Data Sources. A thorough literature search of published English-language articles was performed in the PubMed, Ovid, and Cochrane databases. Review Methods. A database search was conducted with the keywords “CyberKnife” and “vestibular schwannoma” or “acoustic neuroma.” A total of 25 papers were found and reviewed. Data were extracted for patient demographics, number of patients with neurofibromatosis type 2, pretreatment hearing status, tumor size, margin dose, and follow-up duration. The primary outcome variables evaluated were tumor control and hearing preservation. Results. After careful review of the published articles, 11 papers reported data on outcomes of CyberKnife treatment for VS and were included in the analysis, comprising 800 patients studied during 1998 to 2012. The reported mean tumor volume ranged from 0.02 to 19.8 cm3, and the follow-up duration ranged from 6 to 120 months. Margin dose varied from 14 to 25 Gy. The collective mean tumor control rate was 96.3% (95% CI: 94.0%-98.5%). The collective hearing preservation rate was 79.1% (95% CI: 71.0%-87.3%) in 427 patients with measurable hearing. Conclusion. Clinical data on outcomes of CyberKnife radiosurgery for treatment of VSs are sparse and primarily limited to single-institution analyses, with considerable variation in tumor volume and follow-up time. This meta-analysis not only provides an in-depth analysis of available data in the literature but also reviews reported outcomes and complications.

Clinical Results After Single-fraction Radiosurgery for 1,002 Vestibular Schwannomas

“…However, long-term data with reasonably large patient cohorts are missing and few quality-of-life evaluations after SRS for VS have been presented to date [1][2]. Moreover, most published series comprise smaller heterogeneous patient groups treated with inconsistent radiosurgical techniques and doses [3][4][5]. While there has been a tendency to treat increasingly smaller and sometimes asymptomatic tumors, concerns have been raised regarding long-term hearing toxicity and cases of suspected malignant transformation [6][7].…”

Vertigo in Vestibular Schwannoma Patients Due to Other Pathologies

“…Currently, observation, microsurgical resection, or stereotactic radiosurgery (SRS) are the primary treatment modalities for VS patients (3–6). Given that most VSs do not grow and that surgical intervention carries many risks (7,8), some patients are better served with SRS or observation (4).…”

Vestibular Schwannoma: Microsurgery or Radiosurgery

“…The collective hearing preservation rate was 79.1% in 427 patients with measurable hearing. The trigeminal neuropathy rate was 2.0%, facial neuropathy rate was 2.0%, and cerebellar/brainstem toxicity rate was 1.8% [26].…”

“…More recently, an extensive research has been done on the natural history of VS, and it was found that there is a group of VS tumors that grows very slowly or even does not grow at all, and even hearing preservation is sometimes maintained [26]. A study was performed on the natural history of VS less than 2 cm has showed that only 17% of the intrameatal and 28.9% of the extrameatal tumors grew; it was also found that this growth exclusively occurred within 5 years of diagnosis [27].…”