Descriptive Epidemiology of World Health Organization Grades II and III Intracranial Meningiomas in the United States

Objective: Because World Health Organization (WHO) grades II and III meningiomas are relatively uncommon, there is a paucity of literature on the descriptive epidemiology of these tumors. Previous studies are primarily hospital-based case studies, which may overestimate incidence. In addition, much of the literature is before 2000, when the WHO altered the classification of atypical and malignant meningiomas by publishing formal histologic criteria and removing brain invasion as a defining feature of malignancy. Our purpose was to provide a comprehensive and modern population-based study of the descriptive epidemiology of WHO grades II and III meningiomas in the United States.

Methods: The Central Brain Tumor Registry of the United States (CBTRUS), which contains the largest aggregation of population-based data on the incidence of primary brain tumors in the United States, was queried from 2004 to 2010 for intracranial meningiomas categorized by WHO grade. Age-adjusted incidence rates (95% confidence interval) per 100,000 person-years were calculated by age at diagnosis, gender, race, and ethnicity. Annual percent change (APC) was calculated using Joinpoint to characterize temporal trends.

Results: From 2004 to 2010, the age-adjusted incidence of WHO II intracranial meningiomas increased from 0.28 (95% CI, 0.27–0.29) to 0.30 (95% CI, 0.28–0.32), representing an APC of 3.6% (95% CI, 0.8–6.5). Conversely, from 2000 to 2010 the age-adjusted incidence of WHO grade III meningiomas decreased from 0.13 (95% CI, 0.11–0.14) to 0.06 (0.06–0.07), representing an APC of −5.4% (95% CI, −6.8 to −4.0). From 2004 to 2010, the overall proportion of WHO grades I, II, and III intracranial meningiomas was 94.6, 4.2, and 1.2%, respectively. For both WHO grades II and III meningiomas, females had a higher incidence than males at middle ages (range, 35–64 years), whereas males had a higher incidence in older ages (75+ years). Black and Asian Pacific Islander race were both associated with the highest incidence of WHO grades II and III meningiomas. Hispanic ethnicity was not associated with any difference in the incidence of WHO grades II and III meningiomas.

Conclusion: Temporal trends in the incidence of WHO grades II and III meningiomas likely reflect, at least in part, the 2000 WHO histologic criteria revisions. This study presents the most comprehensive evaluation of the descriptive epidemiology of WHO grades II and III meningiomas.