Tumor Control Rate Using LINAC Radiosurgery in the Treatment of Growing Vestibular Schwannomas

Introduction: Radiosurgery is a recognized treatment modality for vestibular schwannoma. Published series have demonstrated a local control rate of 86 to 100% following radiosurgery. Recently published series looking at the natural history of vestibular schwannoma have demonstrated that up to 50% are quiescent over the study interval of up to 4 years. We have undertaken to look at the tumor control rate following radiosurgery in series including only tumors that have been demonstrated to be growing on serial imaging.

Methods: A retrospective chart review was performed that yielded 89 patients with vestibular schwannoma demonstrated to have grown at least 2 mm on serial imaging (gadolinium-enhanced T1-weighted imaging MRI) which were treated with LINAC radiosurgery at our institution between June 1999 and February 2006. Patients were followed with clinical assessment, gadolinium-enhanced MRI, and audiometry at 6- to 12-month intervals after treatment. Minimum follow-up was 2 years. Mean follow-up was 4 years.

Results: Six patients had progressive increase in tumor size after radiosurgery requiring re-referral to a neurosurgeon and evaluation for further treatment (i.e., treatment failures). This yielded a tumor control rate of 93%.

Conclusions: Radiosurgery is effective treatment for vestibular schwannoma that has been demonstrated to be growing prior to treatment.