Abstract
•CKRS affords effective radiographic control of acoustic neuromas.•Hearing preservation after CKRS for acoustic neuromas appears favorable.•Fractionated radiotherapy may reduce radiation toxicity to critical structures.
Fractionated CyberKnife radiosurgery (CKRS) treatment for acoustic neuromas may reduce the risk of long-term radiation toxicity to nearby critical structures compared to that of single-fraction radiosurgery. However, tumor control rates and clinical outcomes after CKRS for acoustic neuromas are not well described. We retrospectively reviewed all acoustic neuroma patients treated with CKRS (2004–2011) in a prospectively maintained clinical and radiographic database. Treatment failure, the need for additional surgical intervention, was evaluated using Kaplan-Meier analysis. For 119 treated patients, median values were 49 months (range, 6–133 months) of follow-up, 1.6 cm3 (range, 0.02–17 cm3) tumor volume, and 18 Gy (range, 13–25 Gy) prescribed dose delivered in 3 fractions (range, 1–5 fractions). Thirty-five of 59 patients (59%) with pre-radiosurgery serviceable hearing (American Academy of Otolaryngology–Head and Neck Surgery class A or B) maintained serviceable hearing at the last audio follow-up (median, 21 months). Two of 111 patients (2%) with facial nerve function House-Brackmann (HB) grade ≤3 progressed to HB grade >3 after radiosurgery. Koos grade IV was predictive of radiographic tumor growth after radiosurgery compared to grades I to III (p = 0.02). Treatment failure occurred in 9 of 119 patients (8%); median time to failure was 29 months (range, 4–70 months). The actuarial rates of tumor control at 1, 3, 5, and 7 years were 96%, 94%, 88%, and 88%, respectively. CKRS affords effective tumor control for acoustic neuromas with an acceptable rate of hearing preservation. Further studies are needed to compare CKRS to single-fraction radiosurgery for acoustic neuromas.