Background: Many incidental meningiomas are detected and need to be assessed for further management. Better knowledge of the long-term natural history is necessary for optimal management.
Methods: We have retrospectively evaluated a cohort of consecutive patients who were referred to the authors at the Department of Neurosurgery with incidentally diagnosed asymptomatic meningiomas from 1991-1998 and followed prospectively. All patients were followed for a minimum of 10 years or until they reached the endpoint of demonstrated tumour growth or died.
Results: During follow-up, 35.4 % of the tumours grew, resulting in a 75 % 15-year growth rate by life-table statistics. The growth rates were similar in smaller (<2 cm) and larger tumours, while calcified tumours grew at a lower rate. The latter difference was, however, not statistically significant.
Conclusion: Long-term tumour growth of incidentally detected asymptomatic meningiomas appeared to be much higher than expected. This information needs to be considered when discussing surgery, since the indication for surgery may be stronger than previously stated, especially for younger patients with tumours that can be reached at low risk.