A prospective study of the natural history of incidental meningioma-Hold your horses!

Abstract

Background: The number of incidental meningiomas has increased because of the increased availability of neuroimaging. Lack of prospective data on the natural history makes the optimal management unclear. We conducted a 5-year prospective study of incidental meningiomas to identify risk factors for tumor growth.

Methods: Sixty-four of 70 consecutive patients with incidental meningioma were included. Clinical and radiological status was obtained at 0, 0.5, 1, 1.5, 2, 3, 4, and 5 years. GammaPlan and mixed linear regression modeling were utilized for volumetric analysis with primary endpoint tumor growth.

Results: None of the patients developed tumor-related symptoms during the study period, although 48 (75%) tumors increased (>15%), 13 (20.3%) remained unchanged, and 3 (4.7%) decreased (>15%) in volume. Mean time to growth was 2.2 years (range, 0.5-5.0 years).The growth pattern was quasi-exponential in 26%, linear in 17%, sigmoidal in 35%, parabolic in 17%, and continuous reduction in 5%. There was significant correlation among growth rate, larger baseline tumor volume (P < .001), and age in years (<55 y: 0.10 cm³/y, 55-75 y: 0.24 cm³/y, and >75 y: 0.85 cm³/y).

Conclusion: The majority of meningiomas will eventually grow. However, more than 60% display a self-limiting growth pattern. Our study provides level-2 evidence that asymptomatic tumors can be safely managed utilizing serial imaging until persistent radiological and/or symptomatic growth.

Keywords: asymptomatic meningioma; incidental meningioma; natural history; prospective study; volumetric tumor growth.

Fig. 1

A, Flowchart illustrating the exclusion and enrollment of incidental meningioma patients, 70 prospective and 62 retrospective patients, referred to the Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway. B, Treatment algorithm for the 64 enrolled prospective patients.

Fig. 2

A, Individual tumor growth curves for all 21 of 48 tumors that increased more than 15% in volume but were continued on conservative treatment because of high age, comorbidity, small tumor volume, or slow growth rate. B, Individual tumor growth curves for 18 of the 21 tumors that increased more than 15% in volume but continued on conservative treatment excluding the 3 largest tumors to better separate the individual curves for the small tumors. C, Kaplan–Meier progression-free survival curve for 64 patients with incidental meningioma followed prospectively for 5 years or until death or documented tumor volume increase of more than 15%. D, Individual tumor growth curves for all 64 prospective patients. E, The principle growth curves observed for the 64 prospective and 38 retrospective tumors included in the study: quasi-exponential, linear, sigmoid, and parabolic growth pattern. F, Individual tumor growth curves for all 38 retrospective patients.