Stereotactic Radiosurgery Improves Tumor Control, Overall Outcomes for Older VS Patients

Managing Vestibular Schwannomas in Older Adults

Vestibular schwannomas present a distinct management challenge in older adults, where decisions must balance tumor control against the risks of intervention and quality of life [1]. For small- to medium-sized tumors, specifically those classified as Koos grade I and II, the choice between active surveillance, microsurgery, and stereotactic radiosurgery (SRS) remains a subject of clinical discussion [2, 3]. While SRS has demonstrated high tumor control rates, often exceeding 90%, the natural history of these benign tumors and the potential for hearing decline regardless of management complicates the decision [4, 5, 6, 7]. Current guidelines emphasize patient counseling on the difficulty of long-term hearing preservation, which declines significantly over time [4, 8]. A recent international multicenter study now provides clarifying data on the outcomes of observation versus SRS, offering a clearer evidence base for managing this specific patient population.

Study Design and Patient Cohort

To better inform management for older adults with small- to medium-sized vestibular schwannomas (VS), an international multicenter study retrospectively compared outcomes between observation and stereotactic radiosurgery (SRS). The researchers focused on patients aged 60 years or older with Koos grade I or II tumors. To mitigate selection bias inherent in a non-randomized study, the investigators used propensity score matching, a statistical method that creates comparable groups by balancing baseline patient characteristics, tumor size, and hearing assessments. This process yielded two well-matched groups of 51 patients each, one for observation and one for SRS. The median age was 68 years in both cohorts, and 35 patients in each group presented with ipsilateral serviceable hearing. The median follow-up was 39 months for the observation group and 27 months for the SRS group, a difference that was not statistically significant (p = 0.5). The primary outcomes measured were freedom from tumor progression, serviceable hearing preservation, and neurological function, including tinnitus, vestibulopathy, and function of the facial and trigeminal nerves, with facial nerve status assessed using the standard House-Brackmann grading scale.

Tumor Control: A Clear Difference

The study's findings on tumor control revealed a stark contrast between the two management strategies. Initial tumor progression was observed in just 2% of patients who received stereotactic radiosurgery (SRS), compared to 52.9% of those managed with observation alone (p < 0.001). This significant difference underscores the efficacy of SRS in halting tumor growth. The durability of this control was evident in the long-term data. The rate of 5-year freedom from tumor progression was 100% in the SRS group, whereas it was only 43% (95% CI 29%-64%) in the observation group. Over a decade, the advantage persisted: the rate of 10-year freedom from tumor progression was 90% (95% CI 73%-100%) for the SRS cohort, while it fell to just 20% (95% CI 8.5%-49%) for the observation cohort. These results demonstrate that SRS provides substantially more effective and durable tumor control than a watchful waiting strategy in this older patient population.

Hearing Preservation and Neurological Outcomes

While tumor control clearly favored radiosurgery, a central question for clinicians is its effect on neurological function, particularly hearing. The study found that at the final follow-up, the rates of hearing loss were statistically indistinguishable between the groups, occurring in 42.9% of the observation cohort and 51.4% of the SRS cohort (p = 0.5). Similarly, rates of serviceable hearing preservation, meaning hearing useful for communication, were comparable. The 3-year serviceable hearing preservation rate was 68% (95% CI 53%-88%) for observation versus 65% (95% CI 49%-85%) for SRS (p = 0.8). At five years, the rate was identical at 53% for both groups (p = 0.8). This suggests that SRS does not impose an additional penalty on hearing preservation compared to the natural course of the disease. However, a more comprehensive picture emerged when researchers analyzed a composite endpoint of either tumor progression or any worsened neurological outcome, including hearing loss, tinnitus, vestibulopathy, or facial or trigeminal nerve dysfunction. The rate of experiencing any of these adverse events was dramatically lower in the SRS group (17.6%) compared to the observation group (66.7%), a highly significant difference (p < 0.001). This indicates that SRS was associated with a much higher likelihood of maintaining overall neurological and radiographic stability.

Clinical Implications for Older Patients

These findings provide direct, clinically relevant guidance for managing Koos grade I or II vestibular schwannomas in patients over 60. The study demonstrates that stereotactic radiosurgery (SRS) provides far superior tumor control compared to observation, with a 10-year freedom from progression rate of 90% versus 20%. Crucially, this significant benefit in tumor control did not come at the cost of worse hearing outcomes; rates of serviceable hearing preservation were comparable between the SRS and observation groups at both three and five years. The most compelling finding for clinical practice may be the composite outcome. Patients in the SRS group had a significantly lower chance of experiencing any negative event, whether tumor growth or neurological decline. The rate of this composite endpoint was 17.6% in the SRS group versus 66.7% in the observation group (p < 0.001). Taken together, the data suggest that for older patients with small- to medium-sized vestibular schwannomas, an upfront SRS approach offers a better chance of achieving long-term tumor control and preserving overall neurological function than a strategy of observation. These results support considering SRS as a primary management option in this patient population.

References

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