RESUMO
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 49â¯months (range, 6-133â¯months) of follow-up, 1.6â¯cm3 (range, 0.02-17â¯cm3) tumor volume, and 18â¯Gy (range, 13-25â¯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, 21â¯months). Two of 111 patients (2%) with facial nerve function House-Brackmann (HB) gradeâ¯≤3 progressed to HB gradeâ¯>3 after radiosurgery. Koos grade IV was predictive of radiographic tumor growth after radiosurgery compared to grades I to III (pâ¯=â¯0.02). Treatment failure occurred in 9 of 119 patients (8%); median time to failure was 29â¯months (range, 4-70â¯months). The actuarial rates of tumor control at 1, 3, 5, and 7â¯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.