Introduction: When meningiomas are small or asymptomatic, the decision to observe rather than treat requires balancing the growth potential of the lesion, patient age and expected longevity with the potential consequences and side effects of treatment. To improve the clinical decision-making process, we aim to characterize the natural growth patterns of presumed meningiomas.
Methods: Patients with presumed meningiomas were identified from tumor-related diagnoses at one institution between 2004 and 2014. Patients were identified who had received no treatment, who had been followed for 2 or more years, and who had 3 or more MRI scans. Tumor dimensions were measured with orthogonal diameters, geometric mean diameters (GMDs) and volumes using the ABC/2 method (simplified ellipsoid volume).
Results: Two hundred and three scans for 34 female (89%) and 4 male (11%) patients were evaluated. Tumor volume ranged from 0.11cc to 14.5cc: the mean and median volumes were 3.18cc and 1.95cc respectively. Follow-¬up times ranged from 24 to 144 months, with a median of 70 months. Regression analysis of the diameters and volumes identified 22 tumors (55%) whose growth rates were not significantly different from zero. Among the remaining 18 tumors, the growth rates had slopes ranging from 0.11 to 1.95 mm/year for the maximum diameter, 0.09 to 1.78 mm/year for GMD and 0.03 to 2.03 cc/year for volume. R^2 values for volume growth ranged from 0.345 to 0.973 with a median of 0.84, which was the highest median among the three measures.
Conclusions: Analysis of scans of a population of untreated patients with presumptive meningiomas demonstrates that approximately half of tumors managed conservatively have zero growth and the remainder have tumor growth that can be approximated with a linear regression model. This allows a quantitative approximation of future growth that should facilitate clinical decision-making regarding management choices.
Patient Care: It will allow practitioners to practice better prognostic decision making with patients with conservatively managed meningiomas.
Learning Objectives: By the conclusion of this session, the participants will be able to: 1) discuss the decision making process behind conservatively managing meningiomas, 2) talk about different measures of assessing tumor growth, 3) bring the quantitative approximation of future growth to bear on clinical decision making.
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