The natural history of vestibular schwannoma growth-prospective 40-year data from an unselected national cohort

Abstract

Background: Optimal management of vestibular schwannoma (VS) is still debated and thus international consensus has not been achieved. Treatment options are observation, radiotherapy, and surgery. Knowledge on the natural history of tumor growth is essential for choice of treatment modality. The aim is to present intra-/extrameatal tumor growth and management data from a prospective, unselected national cohort of patients diagnosed with VS during the period 1976-2015.

Methods: Since 1976, all data from patients diagnosed with sporadic VS in Denmark have been referred to our national treatment center, where they have been entered prospectively into the national database. Data on tumor localization, growth, and treatment were retrieved. Growth definition: >2 mm by linear measurement, in accordance with the Tokyo 2001 consensus-meeting recommendations.

Results: 3637 cases of VS were diagnosed, in which 1304 patients had surgery and 21 received radiotherapy post diagnosis. 2312 patients were observed with mean follow-up of 7.33 years. Of these, 434(19%; 102 intra-and 332 extrameatal tumors) changed to active treatment during the observation period due to tumor growth. 5 years after diagnosis, 21% of the intrameatal tumors exhibited growth during observation, whereas 37% of extrameatal tumors had grown, increasing to 25% intrameatal and 42% extrameatal after 10 years. Following growth, the intrameatal tumors were mostly observed further and the extrameatal mostly underwent surgery. Tumor growth occurred mainly within the first 5 years post diagnosis.

Conclusion: This natural history study documents the growth occurrence of both intra-and extrameatal VS during the first 12 years after diagnosis and should be used in patient counseling, management, and treatment decision making.

Keywords: acoustic neuroma; conservative management; extrameatal; intrameatal; observation; tumor-growth/-size.

© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Figures

Fig. 1

Ideal and actual observation time for patients initially allocated to conservative management. The solid curve is the ideal observation and the dotted curve is the actual observation during the 40-year period. Cumulated actual observation was 70% of the ideal. Definitions explained in the Results section.

Fig. 2

Active treatment for patients initially allocated to observation (n = 434) and patients who died during the observation period (n = 147). The black columns represent the number of patients receiving surgery, the white columns represent radiotherapy-treated patients and the horizontally lined columns represent the patients who died.

Fig. 3

Actuarial “survival” curve of cumulated risk of growth in intrameatal and extrameatal VS with increasing observation length. The gray columns represent the risk for intrameatal tumors. The extension from the gray columns depicted by white columns represent the risk of growth in extrameatal tumors. The horizontally (intrameatal) and vertically (extrameatal) lined columns mark the 5 and 10 year actuarial rates, respectively.

Fig. 4

Kaplan–Meier ”survival” curve of nontreatment in intrameatal and extrameatal VS, depicting the risk of receiving active treatment. The solid curve shows the percentage of purely observed intrameatal tumors during the period and the dotted curve the extrameatal tumors.

Fig. 5

VS treatment algorithm during the first 5 years, subsequently increasing to every 2 years and finally every 5 years.