Identifying Vestibular Schwannomas at Low Risk for Growth

Background: In small- and medium-sized vestibular schwannomas, a starting policy of watchful waiting is justified because of the mild, natural course with relatively minor symptoms, which will not improve by any intervention. As a rule, all patients will have a yearly MRI follow-up. Identifying at time of diagnosis those tumors that likely will not grow is the objective of the study. Methods: The study group contained 155 patients with a unilateral vestibular schwannoma seen in the full 9-year period 2000–2008: continual wait-and-scan (n = 90) and initial wait-and-scan until intervention (65). The median follow-up was 3 years. Growth was defined as more than a 2-mm linear difference in any plane between the diagnostic MRI scan and the last available scan. Univariate and multivariate Cox analyses with backward selection were used to identify protective factors for tumor growth. Findings: Exclusively intracanalicular localization and hearing loss longer than 2 years were significantly associated with no tumor growth. Combining both factors at time of diagnosis resulted in a low-risk group with a Hazard Ratio for growth of 0.26 (0.12–0.54). Further enhanced partition was obtained by including “no growth” at the 2-year MRI follow-up; 94% of this low-risk group indeed did not show growth of their tumors. Interpretation: In our material on vestibular schwannoma patients. 46% start in a wait-and-scan protocol, of which about a quarter may be set apart having low risk for growth. These patients appear not to need yearly MRI checks.