An International Multicenter Matched Cohort Analysis of Stereotactic Radiosurgery Versus Observation for Koos Grade I and II Vestibular Schwannomas in Older Adults

Introduction: Smaller vestibular schwannomas (VS) can be managed with resection, stereotactic radiosurgery (SRS), or observation. The preferred management approach has been debated, however, particularly in older patients with serviceable hearing. This study assesses the safety and efficacy of observation versus SRS for Koos grade I/II VS in older adults, with aim to determine the optimal management strategy for this patient population.

Methods: Multicenter data from patients aged 60 years and older with Koos grade I/II VS managed with observation and SRS was analyzed. Propensity score matching was conducted using patient characteristics, tumor size, and hearing assessments. Outcome measures of tumor control, serviceable hearing preservation (SHP), and neurologic function—including tinnitus, vestibulopathy, House-Brackmann grade, and trigeminal nerve function—were assessed per cohort.

Results: 51 matched patients with median age of 68 years comprised each group. 35 patients per cohort had ipsilateral serviceable hearing at presentation. Median follow-up was 39 months in the observation group versus 27 months in the SRS group (p=0.5). Tumor progression was significantly lower with SRS than with observation (2% versus 52.9%, p< 0.001). 5-year tumor control rate was 100% in the SRS versus 43% in the observation (95% CI: 29-64%) group. 10-year tumor control rate was 90% in the SRS (95% CI: 73-100%) versus 20% in the observation (95% CI: 8.5-49%) group. At last follow-up, there was no significant difference in SHP rates between groups. Composite endpoints of tumor progression and/or worsened neurologic outcome demonstrated a significantly lower rate in the SRS (17.6%) versus observation (66.7%) cohort (p < 0.001).

Conclusion : Management with SRS in older patients with Koos grade I/II VS resulted in significantly superior tumor control rates, comparable hearing preservation rates, and significantly higher rates of favorable overall radiographic and neurologic outcomes than with observation alone. As compared to observation, SRS may be the preferred management option in this patient population.