Epidemiology of meningiomas.

Although they represent about a third of all the tumors of the central nervous system, knowledge concerning meningioma epidemiology (including incidence data and exploration of the risk factors) remains scarce compared to that of gliomas. A limited number of cancer registries worldwide only record malignant brain tumors, however their completeness and accuracy have been questioned. Even if comparisons are made difficult due to differences in methodologies, available annual incidence rates (sex- and age-standardized, generally on US or World standard population), provided by population-based registries range from 1.3/100,000 to 7.8/100,000 for cerebral meningiomas. An increase in the incidence of primary brain tumors in general and of meningiomas in particular has been observed during the past decades in several countries. It has been suggested that this trend could be artefactual and could be the resultant of an ageing population, improvement in health access and in diagnostic procedures, changes in coding classification for tumors recorded in registries, and/or an increase in the rate of histological confirmation, even in the elderly. All these factors are likely to play a role but they might not fully explain the increase in incidence, observed in most age groups. In addition to intrinsic risk factors (gender, ethnic groups, allergic conditions, familial and personal history, genetic polymorphisms), some exogenous risk factors have been suspected to play a role in the etiology of meningiomas and their changes with time is likely to impact incidence trends. A causal link has been established only for ionising radiation but the role of many other factors have been hypothesised: electromagnetic fields, nutrition, pesticides, hormonal as well as reproductive factors. Considering the serious or even lethal potentiality of some meningiomas and the apparent rise in their incidence, all practitioners involved in neuro-oncology should feel concerned today of the necessity to better assess their public health burden and to study their epidemiological features.