Growth of vestibular schwannoma: long-term follow-up study using survival analysis

Background: A vestibular schwannoma (VS) is a benign nerve sheath tumor derived from the vestibular nerves. The growth rate of VS during long-term follow-up has not yet been fully evaluated. We aimed to investigate the growth rate of newly diagnosed VS and the related predictive factors for tumor growth. Methods: A retrospective review was performed using VS patients who underwent at least two magnetic resonance imaging (MRI) scans before tumor growth was observed. Tumor growth was defined as a size increase of more than 2 mm in the longest diameter of the tumor. To assess the growth rate of VS and related factors, we assessed tumor growth using survival analysis. Survival analysis to assess the growth rate and Cox regression analysis were performed to find related factors. Results: The study included 118 patients. The mean age of patients was 57.0 ± 12.9 years. During the observation period, the 5-year cumulative growth incidence rate was 41.3% by survival analysis. Extrameatal tumor location and hearing loss were found to be associated with an increased hazard ratio (HR) for tumor growth. Conclusion: After long-term observation of VS, 41.3% of VS patients presented cumulative growth incidence rate in the first 5 years after diagnosis. Extrameatal tumor location and hearing changes were related to subsequent tumor growth.