Vestibular Schwannoma: Results of Hypofractionated Stereotactic Radiation Therapy

Abstract

Purpose: Our purpose was to study the outcomes of hypofractionated stereotactic radiation therapy (HSRT) in terms of hearing and radiologic response for vestibular schwannomas. Methods and Materials: This was a longitudinal retrospective study at a referral center from 2011 to 2016. All treatments were performed on a Cyberknife device with a dose of 21 Gy (3 × 7 Gy) or 25 Gy (5 × 5 Gy). We assessed tumor response, neurologic outcomes (hearing and facial nerve function), and treatment toxicity. Results: A total of 82 patients were included. Fifty-three patients were treated with the 3 × 7 Gy scheme and 29 with the 5 × 5 Gy. Sixteen patients (20%) had a previous surgery. The median follow-up was 48 months (range, 12-88 months). We noted 3 recurrences leading to a control rate of 96.3%. In our cohort, predictive factors of vestibular schwannoma growth were a tumor volume >2 mm3 and a conformal index <1.1 (P < .0001). The treatment was well tolerated with only 5 grade III acute toxicities (4 vertigo and 1 headache) and no grade IV or V. As for late toxicity, we noticed 2 cases of mild peripheral facial palsy (House and Brackman grade II) in previously operated patients. There was 46.0% hearing preservation among patients with serviceable hearing after HSRT. Conclusions: Our results suggest that HSRT using 3 or 5 fractions is a well-tolerated and effective regimen. These findings are in addition to the few previous hypofractionation studies and contribute to the validity of this treatment modality.