10034-RT-1 Long-term hearing preservation factors following fractionated stereotactic radiotherapy for vestibular schwannoma

Abstract Background Fractionated stereotactic radiotherapy (FSRT) using a linear accelerator is a widely used treatment for vestibular schwannomas. Our previous report suggested that cochlear radiation dose affects post-treatment hearing preservation. While factors such as age, target volume, and pre-treatment hearing have been associated with hearing outcomes after Gamma Knife radiosurgery, long-term data on these factors following FSRT remain limited. Methods We retrospectively analyzed 35 patients with vestibular schwannomas classified as Gardner Robertson (GR) class 1 or 2, treated at our institution between January 2007 and March 2021 with FSRT using 20 Gy in 5 fractions. Results The median patient age was 57 years, with 15 males (42.9%). The median follow-up was 112 months, and the median target volume was 1.09 cc. Tumor control rates were 100% at 5 years and 94. 4% at 10 years. Hearing preservation rates at 5 and 10 years were significantly higher in GR class 1 (54.33% and 40. 75%) than in class 2 (6.67% for both) (p < 0.001). Among GR class 1 patients, cochlear dose strongly correlated with hearing decline (r = 0.722, p = 0.028), while no significant correlation was found in GR class 2 (r = 0.153, p = 0.743). We also evaluated the Pittsburgh Hearing Prediction Score, which incorporates age, GR class, and tumor volume; higher scores were significantly associated with worse hearing outcomes (p = 0.008), consistent with previous Gamma Knife studies. Conclusion This study demonstrates that in FSRT for vestibular schwannomas, cochlear dose has a significant impact on hearing preservation, particularly in patients with good baseline hearing (GR class 1). In such patients, careful dose planning to minimize cochlear exposure is essential. Age and target volume also influence hearing outcomes and should be considered during treatment planning.