What is a Brain Tumor? Understanding symptoms, types, and treatment

What is a brain tumor?

A brain tumor is a growth of cells that develops inside the brain or in tissues closely linked to it, such as the membranes that surround the brain, certain nerves, or the glands located at the base of the skull. In a healthy body, cells grow and divide in a balanced, organized manner. When this process becomes disrupted, cells may begin to multiply too quickly or fail to die when they should. Over time, this can lead to the formation of a tumor.

Not all brain tumors behave in the same way. Some grow slowly and remain in a single area, while others grow more rapidly and may affect nearby brain structures.

It is also important to understand that a tumor does not need to be cancerous to be harmful. The brain is protected inside the skull, a closed and rigid space, so any extra pressure from a growing mass can interfere with functions such as movement, speech, memory, vision, or balance.

Brain tumor types and classification

Brain tumors are classified based on where they originate and how their cells behave. These classifications help doctors determine how the tumor may grow, how it might affect brain function, and what treatment approach is most suitable.

Classification by origin

There are two main origins of brain tumors:

Primary brain tumors

These tumors begin directly inside the brain or in nearby structures such as the meninges, cranial nerves, or pituitary gland. Primary tumors may be benign or malignant. They generally remain within the central nervous system, but some can infiltrate surrounding brain tissue.

Secondary (metastatic) brain tumors

These occur when cancer cells spread to the brain from another part of the body through the bloodstream. Metastatic tumors are always malignant and are more common than primary brain tumors in adults. Cancers that most frequently spread to the brain include lung cancer, breast cancer, melanoma, kidney cancer, and colorectal cancer.

Classification by cell behavior

Tumors are also evaluated based on how their cells look under a microscope:

Benign tumors have cells that look relatively normal and tend to grow slowly.
Malignant tumors contain cells that look abnormal, grow more quickly, and may invade surrounding brain structures.

This assessment contributes to the tumor grade, which indicates how aggressive the tumor is.

Types of brain tumors

Brain tumors are commonly grouped into three main categories: benign brain tumors, malignant brain tumors, and brain metastases.

Benign brain tumors

Benign tumors do not contain cancer cells, and they generally grow at a slower pace. However, even benign tumors can become serious if they compress important brain areas due to the limited space within the skull.

Meningiomas develop in the meninges, the protective layers surrounding the brain. They are often slow-growing and may not cause symptoms until they become larger.
Pituitary adenomas arise in the pituitary gland and may interfere with hormone production, affecting growth, metabolism, or reproductive functions.
Schwannomas develop from the cells that insulate cranial nerves. The vestibular schwannoma is a well-known example that can affect hearing and balance.
Craniopharyngiomas form near the pituitary region. They are usually benign but may cause visual disturbances and hormonal imbalances due to their location.
Pineocytomas arise in the pineal gland and tend to grow slowly, sometimes leading to sleep or vision-related symptoms.

Malignant brain tumors

Malignant tumors are cancerous and grow more aggressively. They may infiltrate nearby brain tissue and have a higher likelihood of recurring after treatment.

Many malignant tumors originate from glial cells, which support nerve cells.

Astrocytomas vary in severity, from slow-growing forms to more aggressive types.
Glioblastoma (GBM) is the most aggressive form of astrocytoma and is one of the most common malignant primary brain tumors in adults.
Oligodendrogliomas generally grow more slowly than some other malignant tumors, but they may still progress over time.
Ependymomas arise in the brain’s ventricular system and may interfere with the flow of cerebrospinal fluid.
Medulloblastomas typically form in the cerebellum and are more common in children, often spreading through the cerebrospinal fluid.
Primary CNS lymphoma is a rare cancer that develops in immune system cells within the brain or spinal cord and often requires specialized treatment.

Brain metastases

Brain metastases occur when cancer spreads to the brain from another organ. They are the most common malignant brain tumors in adults and may appear as a single growth or multiple lesions. Symptoms often develop more rapidly due to the swelling that surrounds metastatic tumors.

The cancers most likely to spread to the brain include lung cancer, breast cancer, melanoma, kidney cancer, and colorectal cancer.

Symptoms of brain tumors

Symptoms of brain tumors differ from one person to another and depend mainly on the tumor’s size, growth speed, and location in the brain. Because each area of the brain controls specific functions, symptoms can affect movement, speech, memory, or behavior depending on where the tumor develops.

General symptoms

These symptoms are linked to increased pressure inside the skull and may appear in both benign and malignant tumors:

Persistent headaches, often worse in the morning or when lying down
Nausea or vomiting without a clear cause
Seizures in someone with no previous history of them
Persistent fatigue or weakness
Visual problems such as blurred or double vision

Symptoms based on tumor location

Frontal lobe: personality or mood changes, difficulty concentrating, weakness on one side of the body
Temporal lobe: memory loss, difficulty understanding or producing speech, hearing changes
Parietal lobe: trouble with coordination, difficulty reading or recognizing objects
Occipital lobe: partial or complete loss of vision
Cerebellum: dizziness, difficulty walking, imbalance
Brainstem: swallowing difficulties, facial weakness, breathing or heart rate irregularities

Hormonal and nerve-related symptoms

Tumors near the pituitary gland may cause hormone imbalance, weight changes, or menstrual irregularities.
Tumors affecting cranial nerves (such as vestibular schwannomas) may cause hearing loss, ringing in the ears, or balance problems.

What can cause brain tumors?

In many cases, the exact cause of a brain tumor remains unclear. What is known is that tumors develop when certain brain cells begin to grow and divide in an uncontrolled way.. While the underlying trigger for this process is often unclear, several factors are known to influence the risk:

Genetic predisposition: Some rare inherited conditions can increase the likelihood of developing brain tumors. These include:

Neurofibromatosis type 1 (NF1 gene)
Neurofibromatosis type 2 (NF2 gene)
Turcot syndrome (APC gene)
Gorlin syndrome (PTCH gene)
Tuberous sclerosis complex (TSC1 and TSC2 genes)
Li-Fraumeni syndrome (TP53 gene)

Age: The risk generally increases with age, although certain tumors such as medulloblastoma are more common in children.

Exposure to ionizing radiation: High-dose radiation to the head, especially from previous medical treatments, is a recognized risk factor.

Weakened immune system: Individuals with reduced immune function may be more susceptible to specific types of brain tumors.

Family history: Although uncommon, having a close family member with a brain tumor may slightly increase risk.

Overall, most brain tumors cannot be traced to a single cause, and they are not typically linked to lifestyle choices or everyday environmental exposures.

How are brain tumors diagnosed?

Diagnosing a brain tumor usually involves several steps to understand its size, location, and type.

Medical history and neurological exam

A doctor will ask about symptoms and test reflexes, coordination, memory, vision, and muscle strength to look for signs of how the brain is being affected.

Brain imaging
These scans help identify the presence and characteristics of a tumor:

MRI (Magnetic Resonance Imaging): The most common and detailed imaging method.
CT scan: Used when MRI isn’t possible or to quickly detect bleeding or swelling.

Additional imaging tests
Sometimes, special scans like MR spectroscopy, functional MRI, or PET scans may be used to learn more about the tumor’s activity.

Biopsy
If imaging suggests a tumor, a biopsy may be performed. A small tissue sample is taken and examined under a microscope to determine whether the tumor is benign or malignant and to identify the exact tumor type.

Genetic and molecular testing
Some tumors undergo specialized testing to understand their genetic profile, which helps guide treatment choices.

Treatment options for brain tumors

Treatment depends on the tumor’s type, size, grade, and location, as well as the patient’s overall health. The goal may be to remove the tumor, slow its growth, or relieve symptoms.

Surgery

Surgery is often considered the first-line treatment, especially when the tumor is in a location accessible to neurosurgeons.

Total Resection: Complete removal of the tumor when it can be safely accessed without damaging critical brain structures.
Partial Resection (Debulking): Performed when the tumor is located near sensitive areas of the brain. Removing part of the tumor can still:
- Reduce pressure inside the skull
- Improve neurological symptoms
- Enhance the effectiveness of other treatments like radiation or chemotherapy

In some cases, minimally invasive or image-guided techniques may be used to improve precision.

Radiation Therapy

This treatment uses high-energy beams (such as X-rays or protons) to destroy cancer cells or stop their growth.

Often recommended after surgery to target any remaining tumor cells.
May be used as the primary treatment if surgery is not possible or safe.
Advanced forms, such as stereotactic radiosurgery (Gamma Knife, CyberKnife),deliver highly focused radiation to minimize damage to healthy tissue.

Chemotherapy

Chemotherapy uses anti-cancer drugs to slow or stop the growth of rapidly dividing tumor cells.

Can be givenorally or through a vein (IV).
Often combined with radiation therapy, especially in aggressive tumors like glioblastoma.
The effectiveness of chemotherapy varies depending on the tumor type and molecular profile.

Targeted Therapy & Immunotherapy

These modern treatment approaches address brain tumors at a molecular or immune-system level.

Targeted Therapy: Focuses on specific mutations or proteins that tumors use to grow. This can limit tumor growth while reducing damage to healthy cells.
Immunotherapy: Helps the immune systemrecognize and destroy cancer cells more effectively. This may include immune checkpoint inhibitors or vaccines being researched in clinical trials.

These treatments are often used when tumors do not respond to conventional therapies or when genetic testing reveals specific targets.

Steroids and supportive care

Medications like steroids reduce brain swelling, while anti-seizure drugs help control seizures, improving comfort and daily functioning.

Rehabilitation

Physical, speech, and occupational therapy may help recovery after treatment, especially if movement, speech, or memory were affected.

Can brain tumors be prevented?

Brain tumors generally cannot be fully prevented because their exact causes are often unclear. However, some measures may help reduce risk or support early detection. Limiting unnecessary exposure to high-dose radiation, particularly in childhood, may lower the likelihood of developing a tumor. People who have a family history of brain tumors or certain genetic conditions may benefit from genetic counseling and periodic medical checkups.

Maintaining overall health through a balanced diet, regular physical activity, adequate sleep, and avoiding smoking supports the immune system.

It is important to note that there is no scientific evidence linking cell phones, Wi-Fi, supplements, or detox products to the development or prevention of brain tumors. While prevention is not always possible, early recognition of symptoms and timely medical care can make a significant difference in outcomes.