Stereotactic radiotherapy in three weekly fractions for the management of vestibular schwannomas

Purpose

This study evaluates the rates of tumor control, hearing preservation and cranial nerve toxicity with the use of CyberKnife stereotactic radiotherapy consisting of 2100?cGy to the 80% isodose line delivered in three weekly fractions to treat vestibular schwannomas.

Materials and methods

Retrospective chart review of vestibular schwannoma patients treated with CyberKnife stereotactic radiotherapy or undergoing watchful waiting between 2006 and 2017 was performed. For inclusion, patients receiving CyberKnife stereotactic radiotherapy must have had pretreatment magnetic resonance imaging and audiography, and 2 follow-up magnetic resonance imaging and audiograms. Watchful waiting patients must have had a minimum of 2 magnetic resonance imaging and 2 audiograms.

Results

Forty patients met inclusion criteria. Twenty-two underwent CyberKnife stereotactic radiotherapy. Eighteen remain in watchful waiting. Crude tumor control was 86.4% at mean radiographic follow-up of 52.3?months. Kaplan-Meier progression-free survival was 76.9% at 5?years. Kaplan-Meier survival from radiographic growth was 61.5% at 5?years. Kaplan-Meier hearing preservation was 17.5% at 5?years. All patients undergoing watchful waiting presenting with serviceable hearing maintained serviceable hearing. Serviceable hearing among CyberKnife stereotactic radiotherapy patients was 42.9% prior to treatment and 14.2% through mean follow-up of 53.7?months. One patient experienced trigeminal nerve toxicity 45?months after SRT. 95.5% of CyberKnife stereotactic radiotherapy patients were complication-free.

Conclusions

Our fractionation regimen provides tumor control consistent with current literature. Hearing outcomes, however, should be discussed with patients prior to CyberKnife stereotactic radiotherapy.