Documented Initial Growth Does Not Necessarily Indicate Treatment for Sporadic Vestibular Schwannomas

Objective To report the natural history of vestibular schwannoma (VS) who elected an initial period of observation and identify prognostic factors. To describe the natural history of growing VS, identify prognostic factors, and review the most recent literature. Study Design Prospective cohort study and literature review. Setting Tertiary referral center. Patients Adult patients diagnosed with a VS between January 1998 and February 2023. Intervention Magnetic resonance imaging surveillance. Main Outcome Measure(s) Growth-free survival and subsequent growth-free survival considering significant growth as a change in size of ≥2 mm. Results Of 430 patients undergoing observation with serial magnetic resonance imaging, 193 (44.9%) demonstrated significant growth at a median of 1.6 years (interquartile range, 0.94–3.51). Of the 193 patients who presented an initial episode of growth, 137 elected to continue to be observed. Of those, 83 (60.6%) presented a second episode of growth at a median of 1.43 years (interquartile range, 1.00–2.49). The subsequent growth-free survival rates (95% confidence interval) at 1, 3, 5, 7, and 10 years were 91.79% (87.26–96.56%), 64.44% (56.56–73.42%), 52.52% (44.23–62.35%), 42.23% (33.92–52.56%), and 36.11% (27.89–46.76%), respectively. Univariate and multivariate Cox regression analyses showed that EC tumor location and initial growth rate were significant predictors of subsequent growth. Conclusions Close observation after documentation of growth is an appropriate management in well-selected cases given that only around 56% of the tumor will continue to grow. Extracanalicular tumor location and initial growth rate are promising prognostic factors to help determine which patient would be a better candidate for close surveillance after initial documentation of growth.