Meningiomas arise from a tangle of interacting causes rather than a single trigger. Ionizing radiation, certain genetic mutations, hormonal influences, and obesity all raise the risk, with the strongest documented environmental factor being prior radiation exposure to the head. Women develop meningiomas roughly twice as often as men, incidence climbs steeply with age, and non-Hispanic Black individuals face higher rates than non-Hispanic White individuals across every age group. Despite being the most common primary brain tumor, meningiomas remain understudied compared with more aggressive cancers, and the picture of what drives them has shifted considerably in the past decade.
The Genetic Landscape
The most frequent genetic driver behind meningiomas is a change in the NF2 gene on chromosome 22. NF2 encodes a protein called merlin, which acts as a kind of scaffolding at the junctions between cells, helping maintain the signals that tell a cell to stop dividing when it contacts its neighbors. When both copies of NF2 are lost or inactivated, that brake on growth disappears. Lab work has shown that restoring merlin in meningioma cells, whether or not they originally carried an NF2 mutation, slows their proliferation.1PubMed. Inhibition of NF2-negative and NF2-positive primary human meningioma cell proliferation by overexpression of merlin due to vector-mediated gene transfer NF2 alterations are the single most common genetic event in meningioma and correlate with tumor location, histological subtype, and how aggressively the tumor behaves.2PubMed Central. Merlin immunohistochemistry is a reliable surrogate marker for NF2 gene alterations in meningioma
But roughly half of all meningiomas lack NF2 mutations entirely. A landmark genomic analysis of 300 tumors uncovered mutations in TRAF7, a protein involved in triggering cell death, in close to one-quarter of all meningiomas. TRAF7 mutations often appeared alongside either a specific change in the transcription factor KLF4 or an activating mutation in AKT1 that ramps up a cell-growth signaling pathway. A smaller fraction, about five percent of non-NF2 meningiomas, carried mutations in SMO, which activates a different growth-signaling cascade. These non-NF2 tumors looked clinically different: they were almost always benign, showed stable chromosomes, and tended to arise from the middle of the skull base.3PubMed Central. Genomic analysis of non-NF2 meningiomas reveals mutations in TRAF7, KLF4, AKT1, and SMO There are still other meningiomas that lack all of these known mutations, pointing to driver genes that haven’t been identified yet.4PubMed Central. Intraventricular meningiomas frequently harbor NF2 mutations but lack common genetic alterations in TRAF7, AKT1, SMO, KLF4, PIK3CA, and TERT
Radiation Exposure
Ionizing radiation is the single best-established environmental risk factor. Both high-dose and low-dose exposure to the head have been linked to later meningioma development, though the relationship is dose-dependent: higher doses both increase the overall risk and shorten the gap between exposure and tumor appearance.5Journal of Neurosurgery. Radiation-induced meningioma Much of the evidence comes from people who received cranial radiation as children, whether for leukemia, other brain tumors, or the now-abandoned practice of irradiating the scalp for ringworm. Cranial radiation during childhood is a firmly established risk factor for meningioma later in life.6JAMA Oncology. Pooled Analysis of Meningioma Risk Following Treatment for Childhood Cancer
Even at lower doses, the risk appears elevated, though exactly how much remains harder to pin down. A case report study notes that while intermediate-to-high-dose exposure is well-characterized as a risk factor, the parameters for low-dose radiation-induced meningioma are still being defined.7PubMed Central. Case report: Low-dose radiation-induced meningioma with a short latency period The practical takeaway is that anyone who received radiation therapy to the head, especially in childhood, should be aware of this long-term risk during routine medical follow-up.
Hormones and the Female Predominance
Meningiomas are roughly twice as common in women as in men, and researchers have long suspected that sex hormones play a role. Many meningioma cells express progesterone receptors. In one study of premenopausal women with meningiomas, half had tumors where 80 percent or more of the cells tested positive for progesterone receptors.8PubMed Central. Meningiomas in Premenopausal Women: Role of the Hormone Related Conditions That receptor presence suggests the tumors can respond to hormonal signals, which may help explain why some meningiomas grow faster during pregnancy or in the luteal phase of the menstrual cycle.
More recent work has focused on estrogen receptor beta (ERβ). A molecular analysis found that ERβ expression was significantly higher in tumors from female patients compared with males and was elevated in higher-grade and recurrent meningiomas. The researchers showed that ERβ appeared to promote aggressive behavior by modulating components of the mTOR signaling pathway, a central regulator of cell growth.9PubMed Central. Molecular mechanisms and therapeutic targeting implications of ER/mTOR signaling axis-driven tumor progression in aggressive meningiomas This matters because it suggests that the hormone connection is not just about whether tumors form but also about how aggressively they behave once they do.
Progestogen Medications
The hormone connection extends beyond the body’s own hormones. Cyproterone acetate, a high-dose synthetic progestogen prescribed for conditions ranging from severe acne to prostate cancer to transgender hormone therapy, has emerged as a clear pharmacological risk factor. A large French cohort study found that women who used high-dose cyproterone acetate faced roughly six to seven times the rate of meningioma requiring surgery or radiotherapy compared with unexposed women. For those with cumulative doses above 60 grams, the risk jumped even further, to about 22 times that of non-users.10BMJ. Use of high dose cyproterone acetate and risk of intracranial meningioma in women: cohort study An earlier population-based study found a similar pattern, with high-dose users showing about an 11-fold increased risk compared with people who never used the drug.11PubMed Central. Risk of meningioma among users of high doses of cyproterone acetate as compared with the general population: evidence from a population-based cohort study
A recent systematic review and meta-analysis pooling data across multiple studies put the overall association at about a 12-fold increased odds for cyproterone acetate users. The same review found that depot medroxyprogesterone acetate, a long-acting injectable contraceptive, carried a smaller but still meaningful elevation in risk, with pooled odds roughly two to three times higher than in non-users.12PubMed Central. Progestogen use and the risk of intracranial meningioma: a systematic review and meta-analysis The French health authority has already restricted prescribing of high-dose cyproterone acetate in response to this evidence. Low-dose formulations, such as those in common oral contraceptive pills, have not shown the same association.
Who Is Most at Risk by Age, Sex, and Race
Meningiomas overwhelmingly affect adults, with incidence rising steeply after age 40 and peaking in the sixth and seventh decades of life. Children and adolescents accounted for less than one percent of meningioma cases in a large U.S. cancer registry analysis. Unlike adults, pediatric patients showed no female predominance, with a roughly equal male-to-female ratio, and had a higher proportion of spinal tumors.13PubMed. Pediatric versus adult meningioma: comparison of epidemiology, treatments, and outcomes using the Surveillance, Epidemiology, and End Results database
Race matters too. A large registry study found that non-Hispanic Black individuals face elevated meningioma rates compared with non-Hispanic White individuals starting in young adulthood and persisting through old age. The disparity was more pronounced for higher-grade tumors: in the seventh decade of life, the rate ratio for grade 2 and 3 meningiomas was about 1.57, compared with about 1.27 for grade 1 tumors. The study also found a synergistic interaction between Black race and male sex, meaning non-Hispanic Black men were at particularly elevated risk relative to non-Hispanic White men.14PubMed Central. Grade-stratified meningioma risk among individuals who are non-Hispanic Black and interactions with male sex The reasons for these racial disparities remain unclear. They may involve genetic susceptibility, differences in environmental exposures, or a combination of both.
Obesity and Metabolic Risk
Body weight is an underappreciated risk factor. A large prospective cohort study reported about a 48 percent increased risk of meningioma among obese individuals compared with those at a normal body mass index.15PubMed Central. Hunting for the causes of meningioma–obesity is a suspect. That finding has been reinforced by additional work showing that both BMI and waist-to-hip ratio are significantly associated with meningioma incidence, along with female sex.16Current Nutrition & Food Science. Body Mass Index and Waist Hip Ratio as a Risk Factor for Meningioma Incidence
The mechanism likely loops back to hormones. Adipose tissue produces estrogen through a process called aromatization. More body fat means more circulating estrogen, which, given the hormone-receptor profile of many meningiomas, could plausibly promote tumor growth. Obesity also drives chronic low-grade inflammation and elevates insulin-like growth factor levels, both of which are biologically plausible contributors. None of this means that losing weight will prevent a meningioma, but it adds meningioma to the growing list of tumors for which excess body fat is a modifiable risk factor.
Inherited Syndromes
Meningiomas arising in the context of an inherited genetic syndrome occur almost exclusively with neurofibromatosis type 2, now called NF2-schwannomatosis. This condition follows an autosomal dominant inheritance pattern and results from germline mutations in the NF2 gene. People with NF2-schwannomatosis often develop multiple meningiomas, along with schwannomas and other nervous system tumors.17PubMed. Inherited genetic syndromes and meningiomas The NF2 gene on chromosome 22 encodes the merlin protein; people born with one faulty copy need only a “second hit” in the remaining copy to lose merlin’s tumor-suppressing function altogether.18Neuro-Oncology Advances. The clinical, genetic, and immune landscape of meningioma in patients with NF2-schwannomatosis
NF2-schwannomatosis is not the only syndrome to consider. Among patients who present with multiple meningiomas but don’t meet standard NF2 diagnostic criteria, about seven percent were found to carry mutations in SMARCE1, and about five percent had mosaic NF2, meaning the NF2 mutation was present in only some of their cells.19PubMed. Multiple Meningiomas as a Criterion for the Diagnosis of Neurofibromatosis Type 2 and Other Tumor Predisposition Syndromes These findings suggest that anyone diagnosed with multiple meningiomas should discuss genetic testing with their care team, even if they don’t have obvious signs of a familial syndrome.
Head Trauma and Mobile Phones
Two commonly feared risk factors deserve their own discussion because the evidence runs against popular belief. The idea that a blow to the head can cause a meningioma has persisted for decades, and a meta-analysis of observational studies did find a statistically significant association, with about double the odds of meningioma after a reported traumatic brain injury.20PubMed Central. Traumatic Brain Injury and Risk of Intracranial Meningioma : A Systematic Review and Meta-Analysis However, the same authors cautioned that this association likely reflects bias rather than biology: people diagnosed with meningioma may be more likely to recall past head injuries, and surveillance after a head injury may simply detect tumors that were already there. A Mendelian randomization study, which uses genetic variants to test for causation and is less prone to these biases, found no causal relationship between any type of traumatic brain injury and meningioma.21PubMed. Traumatic Brain Injury Increasing Risk of Meningioma? From the Genetic Evidence The weight of the evidence currently leans against head trauma as a true cause.
Mobile phone use is another frequent concern. A large prospective cohort study called COSMOS tracked participants for a median of about seven years and found no meaningful increase in meningioma risk with increasing hours of call time. The adjusted hazard ratio per 100 cumulative hours of phone use was essentially 1.0.22PubMed. Mobile phone use and brain tumour risk – COSMOS, a prospective cohort study An earlier case-control study similarly found no increased meningioma risk among regular mobile phone users and no dose-response relationship with measures of radiofrequency exposure.23British Journal of Cancer. Mobile phone use, exposure to radiofrequency electromagnetic field, and brain tumour: a case–control study The consistency of null findings across study designs makes it unlikely that mobile phones contribute to meningioma risk.
How Pediatric Meningiomas Differ
When meningiomas do appear in children, they are not simply small versions of adult tumors. Molecular profiling shows that pediatric meningiomas cluster separately from adult cases and are characterized by distinct features. While NF2 alterations are frequent in childhood meningiomas, the other common mutations seen in adult tumors, such as those in TRAF7, AKT1, KLF4, and SMO, are typically absent.24PubMed Central. Molecular profiling of pediatric meningiomas shows tumor characteristics distinct from adult meningiomas Pediatric meningiomas also show a higher proportion of the clear cell histological subtype, tend to appear in different locations, and are more often associated with germline mutations, meaning the child was born with a predisposing genetic change rather than acquiring it through environmental exposure.25Neuro-Oncology Advances. Pediatric meningiomas: A literature review and diagnostic update This distinction has practical implications: a meningioma in a child should prompt a more thorough genetic workup than one discovered in a 60-year-old.
Incidental Meningiomas and Watchful Waiting
A growing number of meningiomas are found by accident on brain imaging done for unrelated reasons like headaches or dizziness. These incidental meningiomas raise a natural question: if you have one, how worried should you be? A prospective study followed incidental meningiomas for up to 12 years and found that while growth was the natural trend, it tended to decelerate after about a year and a half and became statistically insignificant after eight years. About 63 percent of tumors showed a self-limiting growth pattern. Within five years, almost all interventions that would ultimately be needed had already been initiated, and no patient developed symptoms before intervention was offered. More than 40 percent of patients with indolent tumors avoided treatment entirely, and roughly 31 percent of the cohort died of unrelated causes without their meningioma ever becoming a problem.26PubMed Central. Growth dynamics of incidental meningiomas: A prospective long-term follow-up study
A more recent study developed a clinical tool to stratify incidental meningiomas into risk categories. Tumors classified as low risk had a progression rate of only about 4 percent, while medium-risk tumors progressed about 24 percent of the time and high-risk tumors about 52 percent of the time. The five-year progression-free survival across the whole cohort was about 88 percent.27PubMed Central. A Clinical Tool to Identify Incidental Meningioma for Early Outpatient Management For people with a small, incidentally discovered meningioma, periodic imaging and clinical follow-up is often the appropriate first step rather than immediate surgery.
What Predicts Recurrence After Surgery
Even among grade 1 meningiomas, which are the least aggressive, recurrence is not rare. The factors that predict it most reliably are how completely the tumor was removed and how fast its cells were dividing. In one analysis, subtotal resection (leaving some tumor behind because of its location near critical structures), posterior fossa location, nuclear atypia, and a high cell proliferation index were all independently associated with recurrence. Patients who had a complete resection but whose tumors had a proliferation index above about 4.5 percent recurred at roughly the same rate as those who had incomplete removal.28PubMed Central. WHO Grade I Meningioma Recurrence: Identifying High Risk Patients Using Histopathological Features and the MIB-1 Index Tumor size and extent of resection were also identified as independent predictors of recurrence in a separate study that built a nomogram for risk stratification.29PubMed. A Nomogram Model for Stratifying the Risk of Recurrence in Patients with Meningioma After Surgery
This means the pathology report matters enormously. A grade 1 meningioma that was fully removed and showed low proliferative activity has an excellent prognosis. The same grade with incomplete removal or brisk cell division warrants closer surveillance. Patients should ask their neurosurgeon and neuropathologist about both the completeness of resection and the Ki-67 or MIB-1 index to understand where their individual tumor falls on the risk spectrum.
Molecular Subtyping and DNA Methylation
Traditional grading based on what a tumor looks like under the microscope does not always capture how it will behave. Researchers have turned to DNA methylation profiling, a way of reading the chemical marks on a tumor’s genome, to sort meningiomas into more biologically meaningful categories. One study identified four methylation-based subgroups: Malignant, Intermediate, Benign A, and Benign B. Specific mutations tended to cluster within particular methylation groups, with NF2, AKT1, SMO, and TRAF7 mutations each associating with distinct subgroups.30PubMed. DNA methylation profiling of meningiomas highlights clinically distinct molecular subgroups
An earlier landmark analysis identified a methylation subgroup with an unfavorable prognosis that carried complex chromosomal losses, including losses on chromosomes 1p, 6q, 14q, and 18q, all previously flagged as indicators of poor outcome. These methylation signatures correlated with recurrence risk better than traditional histological grading in many cases.31PubMed Central. Global epigenetic profiling identifies methylation subgroups associated with recurrence-free survival in meningioma This kind of molecular classification is gradually working its way into clinical practice. For patients with tumors that seem borderline or behave unexpectedly, methylation profiling can provide a more accurate picture of what to expect.
The Tumor Immune Microenvironment
One of the more surprising recent findings is how much the immune cells inside a meningioma influence its behavior. Tumor-associated macrophages, a type of immune cell that infiltrates many solid tumors, show up in large numbers in meningiomas. The trouble is that most of them, more than 80 percent in one analysis, are the “M2” type that actually supports tumor growth rather than fighting it. M2 macrophage density correlated with tumor size, and the balance between tumor-fighting M1 macrophages and pro-tumor M2 macrophages shifted dramatically in higher-grade and recurrent tumors.32PubMed Central. Tumor-associated macrophage infiltration in meningioma
A larger follow-up study confirmed that high infiltration by pro-tumoral macrophages was an independent predictor of poor survival and actually counteracted the benefits of having tumor-infiltrating lymphocytes, which are ordinarily a good prognostic sign in cancer. The presence of abundant macrophages created an immunosuppressive niche inside the tumor, essentially shielding it from the immune system.33PubMed Central. Tumor-associated macrophages in meningiomas: a novel biomarker for poor survival outperforming the benefits of T cells This line of research opens the door to immunotherapy strategies targeting the macrophage population, a therapeutic avenue that is still early-stage but could eventually change how aggressive meningiomas are treated.
Where the Cell of Origin Debate Stands
For over a century, textbooks have stated that meningiomas come from arachnoid cap cells, a specific type of cell in the membranes covering the brain. Recent work using advanced techniques like single-cell sequencing and transgenic animal models has started to challenge that assumption, suggesting the cellular origin is more varied and complex than previously believed.34PubMed Central. Current evidence on the cell of origin of meningiomas disputes the arachnoid cap cell dogma This might sound like a purely academic question, but identifying the true cell of origin has real consequences for developing targeted therapies. If meningiomas can arise from more than one cell type, treatments designed to exploit the vulnerabilities of one cell type may not work for all patients. The field is still in flux, and the classic “arachnoid cap cell” story is likely to be revised further as more data accumulate.