Brain tumors are relatively uncommon compared to other cancers, but they’re far from rare. An estimated 107,100 new cases of primary brain and central nervous system tumors will be diagnosed in the United States in 2025 alone. That translates to roughly 6.1 new cases per 100,000 people each year. To put that in perspective, brain cancer accounts for a small fraction of all cancer diagnoses, yet the numbers add up to tens of thousands of people affected annually.
Most Brain Tumors Are Not Cancerous
One of the most important distinctions in brain tumor statistics is the split between benign and malignant growths. Approximately 74% of all brain tumors are benign, meaning they don’t invade surrounding tissue or spread to other parts of the body. The remaining 26% are malignant. This ratio surprises many people, who tend to associate brain tumors almost exclusively with aggressive cancers like glioblastoma.
Meningiomas, which grow from the membranes surrounding the brain, are the single most common type. They account for about 37.6% of all primary brain and spinal cord tumors and occur at a rate of 8.6 per 100,000 people per year. Most meningiomas are benign and slow-growing. Many are discovered incidentally during brain scans done for completely unrelated reasons, like a head injury or chronic headaches.
How Often Brain Tumors Show Up by Accident
A large study analyzing over 16,400 brain MRIs from research volunteers (people scanned for studies, not because they had symptoms) found that about 4% had an incidental finding significant enough to warrant medical follow-up. Of those flagged findings, roughly 21% were potentially tumor-related. The majority of scans, about 83%, came back completely normal.
This means that a small but real percentage of people are walking around with brain abnormalities they don’t know about. Most of these turn out to be benign growths like meningiomas or cysts that never cause symptoms and may never need treatment. Still, the data helps explain why brain tumor diagnoses sometimes feel sudden: the tumor was likely growing silently for months or years before anything prompted a scan.
Metastatic Tumors Are More Common Than Primary Ones
The 107,100 figure covers only primary brain tumors, meaning tumors that originate in the brain itself. Secondary brain tumors, which spread to the brain from cancers elsewhere in the body (lung, breast, melanoma, and others), are actually more frequent. About 15% of all cancer patients develop brain metastases at some point during their illness, and that number may be rising as treatments for other cancers improve and patients live longer.
When you combine primary and metastatic cases, the total number of people dealing with a brain tumor in any given year is substantially higher than the primary-tumor statistics suggest.
Who Gets Brain Tumors
Brain tumors can occur at any age, but the patterns vary dramatically by tumor type. In children, the incidence of brain and nervous system tumors is about 2.9 per 100,000 per year. The most common childhood types are pilocytic astrocytomas, medulloblastomas, and other gliomas. Brain tumors are actually the most common solid tumor in children, even though the overall rate is lower than in adults.
Gender plays a measurable role. Males are about 60% more likely to develop glioblastoma, the most aggressive primary brain cancer, than females. Meningiomas, on the other hand, are diagnosed more often in women, particularly after middle age.
Race and ethnicity also influence which types of brain tumors appear most frequently. Black patients are significantly overrepresented in pituitary adenomas, making up 35% of those cases despite being a smaller share of the overall population. White patients account for a disproportionately high share of glioblastomas (90% of cases) and other gliomas with specific molecular profiles. Asian patients show higher rates of certain glioblastoma subtypes. These differences likely reflect a combination of genetic susceptibility and, in some cases, disparities in who gets scanned and diagnosed.
Known Risk Factors
For most brain tumors, the cause is unknown. The one firmly established environmental risk factor is ionizing radiation. A major European study tracking children and young adults who received CT scans found a clear dose-response relationship: the more radiation exposure to the head, the higher the risk of developing a brain tumor later. For every 100 milligray of radiation absorbed, the excess risk of brain cancer roughly doubled. That said, the absolute risk from a single CT scan remains very small. The finding is most relevant for people who’ve had repeated imaging during childhood or who received radiation therapy to the head for a prior cancer.
A small percentage of brain tumors are linked to inherited genetic conditions, such as neurofibromatosis or Li-Fraumeni syndrome. But these account for a minority of cases. For the vast majority of people diagnosed with a brain tumor, there’s no identifiable cause.
Survival Varies Enormously by Type
Because “brain tumor” covers everything from a slow-growing meningioma that may never need treatment to an aggressive glioblastoma, survival statistics span a huge range. Many benign tumors can be monitored for years or removed surgically with excellent outcomes. Some never require intervention at all.
Glioblastoma sits at the other end of the spectrum. It is the most common malignant primary brain tumor in adults, and it remains one of the hardest cancers to treat. Only about 5% to 7% of people with glioblastoma are alive five years after diagnosis. Median survival with standard treatment is roughly 15 months, though individual outcomes vary based on the tumor’s molecular characteristics, location, and how completely it can be removed.
Lower-grade gliomas and many other tumor types fall between these extremes, with five-year survival rates that can range from 30% to over 90% depending on the specific diagnosis. The molecular classification of brain tumors has become increasingly precise in recent years, which means prognosis is more individualized than the broad category of “brain tumor” might suggest.