Brain tumors: Full guide

What is a brain tumor?

A brain tumor is a growth of abnormal cells in or near the brain. Some brain tumors are cancer and some are not. Even a tumor that is not cancer can cause problems, because the skull has little room to spare.

A primary brain tumor starts in the brain. The most common ones in adults are meningiomas and gliomas. A glioma starts in the support cells of the brain, called glial cells. Glioblastoma is the most common fast-growing primary brain cancer in adults.

Brain metastases are different. They are cancers that started somewhere else, like the lung, breast, or skin, and spread to the brain. They are treated based on where the cancer started.

Brain tumors can cause headaches, seizures, weakness, speech trouble, vision changes, or changes in thinking and mood. Doctors now use gene tests on the tumor to name the exact type. This helps them plan treatment. Your care team will explain what your type means for you.

Types

Glioblastoma

A fast-growing grade 4 glioma. It is the most common primary brain cancer in adults. It is treated with surgery, radiation, and chemotherapy, and it often comes back.

Astrocytoma, IDH-mutant

A glioma with a gene change called IDH. It usually grows more slowly than glioblastoma and is more common in younger adults. It can be grade 2, 3, or 4.

Oligodendroglioma

A glioma that has both an IDH gene change and a loss of parts of two chromosomes (called 1p/19q codeletion). It is rare. It often grows slowly and responds well to treatment.

Meningioma

The most common primary brain tumor. It grows from the thin covering of the brain, not the brain itself. Most are not cancer. Small ones without symptoms are often just watched with MRI scans.

Brain metastases

Cancer that spread to the brain from another part of the body. They are the most common brain tumors in adults. Lung, breast, and melanoma (skin cancer) are the most common sources.

Primary CNS lymphoma

A lymphoma (cancer of immune cells) that starts in the brain, spinal cord, or eyes. It is treated with strong chemotherapy, not usually with surgery.

Ependymoma and medulloblastoma

Less common tumors. They are more often seen in children, but adults can get them. They are usually treated with surgery and radiation, sometimes with chemotherapy.

Diffuse midline glioma

A rare, fast-growing glioma in the middle parts of the brain, such as the brainstem. It is more common in children and young adults. Many have a gene change called H3 K27M.

Tests you may have

MRI with contrast

The main test for brain tumors. It uses magnets and a dye given by IV to make detailed pictures. It shows the size and place of the tumor and is used to check on it over time.

CT scan

A fast X-ray scan of the head. It is often the first scan in the emergency room. MRI shows more detail.

Neurological exam

Your doctor checks your strength, feeling, balance, reflexes, vision, speech, and memory. It shows how the tumor may be affecting you.

Biopsy or surgery

Removing some or all of the tumor to look at under a microscope. For most gliomas, this is the only way to know the exact type and grade.

Tumor gene testing

Tests on the tumor tissue look for changes like IDH, 1p/19q, and MGMT. These results are now part of the diagnosis itself and help guide treatment.

EEG

A test that records the brain's electrical activity with small pads on the scalp. It can help if you have had seizures or spells.

Spinal tap (lumbar puncture)

A thin needle in the lower back takes a small sample of the fluid around the brain and spine. It is used for some tumors, like lymphoma or medulloblastoma, to see if cells have spread.

Body scans and eye exam

If cancer may have spread from another place, you may need CT or PET scans of the body. If lymphoma is suspected, an eye doctor will check your eyes.

What the grade means

Most brain tumors are not staged like other cancers, because primary brain tumors rarely spread outside the brain. Instead, doctors use a grade.

The grade goes from 1 to 4. It tells how fast the tumor is likely to grow. Gene test results can change the grade, even if the tumor looks slower under the microscope.

For brain metastases, the stage of the original cancer matters most. Your care team will look at the number, size, and place of the spots in the brain.

Grade 1

Slow-growing and often well defined. Some can be cured with surgery alone. Most meningiomas are grade 1.

Grade 2

Grows slowly but spreads into nearby brain tissue. It can turn into a higher grade over time. Some people are watched closely, and some get treatment after surgery.

Grade 3

Grows faster. Treatment usually includes surgery, then radiation and chemotherapy.

Grade 4

The fastest-growing grade. All glioblastomas are grade 4. Treatment usually includes surgery, radiation, and chemotherapy.

Brain metastases

One or a few spots can often be treated with focused radiation or surgery. Many spots may be treated with radiation to the whole brain or with medicines that reach the brain.

Tumor markers and gene tests

Brain tumors are now named partly by their gene changes. Two tumors that look the same under a microscope can act very differently.

These tests help predict how the tumor will behave and which treatments may work best. Ask your care team which tests were done on your tumor and what they showed.

IDH

A gene change found in many slower-growing gliomas. Tumors with an IDH change usually do better than tumors without it. A pill called vorasidenib targets IDH in some grade 2 gliomas.

1p/19q codeletion

A loss of parts of chromosomes 1 and 19. Together with an IDH change, it means the tumor is an oligodendroglioma. These tumors respond well to radiation and chemotherapy.

MGMT methylation

MGMT is a gene that helps cells fix damage. When it is switched off (methylated), the chemotherapy pill temozolomide tends to work better. It is an important test in glioblastoma.

CDKN2A/B

If both copies of this gene are missing in an IDH-mutant astrocytoma, the tumor is called grade 4.

TERT, EGFR, and chromosome 7 and 10 changes

In certain gliomas without an IDH change, these findings mean the tumor is a glioblastoma, even if it looks lower grade.

H3 K27M

A gene change that defines a type of midline glioma. A newer pill called dordaviprone is approved for some of these tumors when they come back.

BRAF and NTRK

Rare gene changes in some brain tumors. Targeted pills may work when these are present.

Main treatments

Surgery

The surgeon removes as much tumor as is safe without harming important brain areas. This is called maximal safe resection. It eases pressure and gives tissue for testing.

Radiation therapy

High-energy beams aimed at the tumor area. For gliomas, it is usually given on weekdays over a few weeks. Older adults may get a shorter course.

Stereotactic radiosurgery (SRS)

Very precise, high-dose radiation given in one or a few sessions. It is not real surgery. It is often used for brain metastases and some meningiomas.

Chemotherapy

Medicines that kill cancer cells. Temozolomide is a pill often used with and after radiation for glioblastoma and other gliomas. A mix of three medicines called PCV is used for some gliomas.

Targeted therapy

Medicines that block a specific gene change in the tumor. Examples include vorasidenib for some IDH-mutant gliomas. For brain metastases, some targeted pills for lung cancer, breast cancer, and melanoma work well in the brain.

Tumor treating fields

A device worn on the shaved scalp that sends mild electric fields into the brain. It can be used with temozolomide after radiation for glioblastoma. It needs to be worn most of the day.

Steroids

Medicines like dexamethasone lower swelling around the tumor. They can ease headaches and other symptoms quickly. Your team will try to use the lowest amount for the shortest time.

Seizure medicines

If you have had a seizure, you will take medicine to prevent more. If you have never had a seizure, these medicines are usually not needed.

Watchful waiting

Some slow-growing tumors, like small meningiomas or some low-grade gliomas, can be watched with regular MRI scans. Treatment starts if the tumor grows or causes symptoms.

Clinical trials

Research studies that test new treatments. They are an important option for many brain tumors, especially glioblastoma. Ask if a trial is right for you.

Common side effects and what helps

Fatigue

Feeling very tired is common during and after radiation. Short walks and rest breaks help. Plan important tasks for the time of day you feel best.

Steroid side effects

Steroids can cause trouble sleeping, hunger, high blood sugar, mood changes, and weak leg muscles. Take them in the morning if your team agrees. Never stop them suddenly on your own.

Seizures

Take seizure medicine every day as directed, even when you feel fine. Get enough sleep and avoid alcohol. Caregivers should learn basic seizure first aid.

Thinking and memory changes

The tumor and its treatment can affect memory, focus, and planning. Use notes, phone reminders, and routines. Ask about a rehab specialist or speech therapist who can help.

Low blood counts

Temozolomide and other chemotherapy can lower blood counts. You will have regular blood tests. Call right away if you have a fever or unusual bleeding or bruising.

Nausea and constipation

Anti-nausea medicine taken before temozolomide often helps. Eat small meals. Drink fluids, and ask about stool softeners.

Hair loss and scalp irritation

Radiation can cause hair loss where the beams enter, and the scalp can get red or itchy. Use gentle shampoo and protect your head from the sun. Ask before using any creams.

Headaches and swelling

Swelling after surgery or radiation can cause headaches. Tell your team about headaches that get worse, especially with vomiting or vision changes.

Mood and personality changes

Some people feel sad, anxious, or more irritable. This can come from the tumor, steroids, or stress. Tell your team, because there is help for this.

Living with and after a brain tumor

You will have regular MRI scans, often every few months at first. Sometimes a scan after radiation looks worse even though the tumor is not growing. This is called pseudoprogression. Your team may repeat the scan before changing treatment.

Driving rules after a seizure or brain surgery depend on your state. Most people must stop driving for a period of time. Ask your care team when it is safe and legal for you to drive again.

Rehab can help a lot. Physical, occupational, and speech therapists help with strength, balance, daily tasks, and speaking.

A brain tumor can change how a person thinks, feels, or acts. This can be hard for families. Caregivers need support too. Social workers and support groups can help.

It is wise to talk early about your goals and wishes. Choose someone who can make medical decisions if you cannot. Palliative care can help with symptoms and support at any stage.

If you work, ask about job protections, disability, and time off. A social worker can help you sort out these options.