Cancer starts when cells change (mutate) and grow out of control. The changed or abnormal cells often grow to form a lump or mass called a tumor. Cancer cells can also grow into (invade) nearby areas. They can spread to other parts of the body, too. This is called metastasis.

Glioblastoma multiforme (GBM) is a rare cancer that starts in the brain. But it's the most common primary brain tumor in adults. It's a very fast-growing tumor that tends to spread to nearby normal brain tissue.

GBMs start from glial cells in the brain. GBMs are a type of astrocytoma. They start in a type of glial cell that is star-shaped called astrocytes. Astrocytes help support nerve cells and carry nutrients to them.

Brain tumors are graded on a 1 (I) to 4 (IV) scale based on how fast they grow. Grade I brain tumors grow very slowly and rarely spread into nearby tissues. Grade IV are the most aggressive. GBMs are grade IV astrocytomas. They are often found in the brain's frontal lobes (located directly behind the forehead) and temporal lobes (located near your temples and ears inside the skull). But they can also develop in other lobes of the brain. They grow quickly and often invade nearby brain tissue. They rarely spread to other parts of the body (metastasize).

These tumors are rarely cured. But treatment can help people live longer by controlling tumor growth. GBMs tend to occur between ages 65 and 74, but they can happen at other ages, too. They're very rare in children.

Experts are still trying to understand what causes GBM. Astrocytes are usually very controlled and organized cells. Something happens that causes them to start multiplying and forming tumors. It's not clear what causes this, but researchers have found a number of changes, or mutations, in genes within the tumor cells. Some of these mutations affect the ability of the cells to control themselves.

Most GBMs start as GBMs. Rarely, a lower-grade tumor will transform into a GBM over time.

Most people with GBM have no family history or risk factors that can be identified. Some family inherited syndromes like Li-Fraumeni syndrome, neurofibromatosis, and Lynch syndrome might increase risk of developing GBM. Exposure to ionizing radiation to the brain as a child may also increase risk.

Your brain controls your thoughts, emotions, and actions. It also interprets information from your senses like what you see, hear, and touch. Different areas of the brain control different functions. Some of the symptoms of GBM have to do with where the tumor starts. For instance, if it grows in an area that controls your arm movements, your arm may become weak. If it grows in an area that controls your speech, you may have trouble forming words.

As the tumor continues to grow, it starts to take up space. This increases the pressure within the skull. Some of the symptoms of GBM are caused by the increased pressure in the brain (also called increased intracranial pressure).

Many GBM symptoms develop slowly and get worse over time. These may include:

• Headaches (often the first symptom)
• Loss of appetite
• Loss of balance or trouble walking
• Mood swings
• Nausea and vomiting
• Personality and behavior changes
• Problems speaking
• Problems with memory
• Seizures
• Sensation changes
• Trouble concentrating
• Vision changes like blurred or double vision
• Weakness
• Stroke-like symptoms

Many of these symptoms may be caused by other health problems. Still, it's important to see a doctor if you have these symptoms. Only a doctor can tell if you have cancer.

Your doctor will likely start by asking you some questions. You'll be asked about your recent symptoms and your personal and family history of disease. Physical and neurological exams will be done to check your vision and hearing, sensations of touch, strength, and reflexes. You may also be asked questions to assess your memory and learning ability. You may be asked to walk or do other activities to look at your gait, coordination, and balance.

If your doctor thinks you might have a brain tumor, you'll need more tests. These tests can help tell the difference between tumors and infections, abscesses, strokes, and other possible causes of your symptoms. They'll also help find out exactly where the tumor is and how it's affecting the rest of the brain. The tests used might include:

• MRI. This is the preferred first test used to help find tumors, areas of swelling or blood build-up in the brain, and areas affected by stroke. It can also show nerves and blood vessels around the tumor.
• CT scan. This test is used when an MRI can't be done. It can help find areas of fresh bleeding, skull bone changes, and calcium deposits.
• Magnetic resonance spectroscopy (MRS). This test measures metabolites biochemical processes in tumors and normal tissue in different parts of the brain. It can be done as part of an MRI.
• Stereotactic needle biopsy. A CT scan or MRI is used to guide a needle into the tumor to take out a small piece of it (sample) for testing by a pathologist. The pathologist will do molecular tests to find specific genes, proteins, and other molecules in a tumor. This helps with making a diagnosis and choosing the best treatment plan.
• Blood or other tests. These can help show how well certain organs are working and give an idea of your overall health.

Your doctor will probably refer you to a specialist to help make the diagnosis. This can include a neurologist or neurosurgeon. There may be other specialists that help plan your treatment, such as oncologists or neuro-oncologists.

Treatment of GBM usually involves doctors from many specialties, such as neurosurgery, neuro-oncology, and radiation oncology. It also includes other health care professionals on your team, such as social workers, nurses, dietitians, and occupational or physical therapists. They all work together to figure out the best way to treat and manage your GBM.

Your treatment will depend on your age, your overall health, your preferences, the size of the tumor, its location in your brain, and results of molecular tests. While GBM rarely spreads from the brain to a different part of the body, it often spreads within the brain.

Some people choose to get only palliative care. This means treatment is not focused on treating the cancer. It's used to control symptoms, keep you comfortable, and give you the best quality of life possible.

Other people choose active cancer treatment. This commonly starts with surgery to remove as much of the tumor as possible while keeping as much brain function as possible. MRI might be used during the surgery to help guide the surgeon to the areas to take out. The removed tumor is then sent to a lab, where tests are done to know for sure that it's GBM, another type of tumor, or something else.

Taking out even part of the tumor can help relieve pressure in the brain. Some people have surgery even if a large part of the tumor can't be removed.

An MRI after surgery can help find any remaining tumor or swelling. Even with the best surgical methods, some tumor cells may remain, which means more treatment will be needed. During surgery, your surgeon may put chemotherapy wafers where the tumor was. The wafers slowly release the chemo medicine right where the cancer cells are.

Depending on your age and overall health, you may need more treatments. They may include:

• Chemotherapy (given into your blood or by pills)
• Radiation therapy
• Medicines to reduce swelling in the brain, such as corticosteroids
• Medicines to stop seizures
• Palliative care to ease symptoms you may be having
• Participation in a clinical trial, which may offer you more treatment choices
• Alternating electric field therapy (the use of low-energy electric fields to treat the brain tumor), also called tumor-treatment fields therapy

You'll need regular follow-up to see how you are responding to treatment and to watch for signs that the GBM has come back (recurred). This will include regular exams and MRIs. You may need a positron emission tomography (PET) scan if it looks like the GBM has recurred. PET scans can help show whether a change in the brain is related to treatment or is tumor recurrence.

If the GBM returns, you'll have the choice of getting more treatment, which may include:

• More surgery, which may include placement of wafers
• Chemotherapy
• Targeted therapy
• Repeat radiation therapy
• Palliative care
• Participation in a clinical trial

A number of clinical trials are taking place to learn more about promising new treatment choices. Some people decide to take part in clinical trials because it's a way to get the newest treatments available, and they may help people who have the same problem in the future.

Talk with your doctors about your treatment choices. Make a list of questions. Think about the benefits and possible side effects of each choice. Talk about your concerns with your doctor before making a decision.

If untreated, GBM can quickly grow and spread through the brain. This can lead to ongoing functional loss and increasing intracranial pressure. Headaches, seizures, personality changes, and unstable moods are common.

Treatment can also lead to complications. These may include:

• Depression
• The tumor coming back after treatment (recurrence)
• Side effects of steroid treatment, such as trouble sleeping, increased risk of infection, weight gain, and mood swings
• Other treatment side effects, such as increased risk of infection or bleeding due to chemotherapy and changes in brain function from surgery and radiation

Talk with your treatment team about risks linked to your treatment so you know what you might expect and watch for. Let them know about any problems you're having. There are often ways to prevent or control side effects.

Many people feel worried, depressed, and stressed when dealing with cancer. Getting treatment for cancer can be hard on the mind and body. Keep talking with your health care team about any problems or concerns you have. Work together to ease the effect of cancer and its symptoms on your daily life.

Here are some tips:

• Talk with your family or friends.
• Ask your health care team or social worker for help.
• Speak with a counselor.
• Talk with a spiritual advisor, such as a minister or rabbi.
• Ask your health care team about medicines for depression or anxiety.
• Keep socially active.
• Join a cancer support group in person or online.

Cancer treatment is also hard on the body. To help yourself stay healthier, try to:

• Eat a healthy diet with a focus on high-protein foods.
• Drink plenty of water, fruit juices, and other liquids.
• Keep physically active.
• Rest as much as needed.
• Talk with your health care team about ways to manage treatment side effects.
• Take your medicines as directed by your team.

You'll be seeing doctors and many other medical specialists on your team. Ask them any questions you may have. If you have side effects, have trouble getting to your appointments, or are facing challenges in your personal life, make sure they know. Also, be aware that depression is a common problem. Ask to see a mental health counselor, psychologist, or psychiatrist if you need one. They can help you cope with what's going on. Family members may also suffer from anxiety and depression and can benefit from counseling services.

• GBM is the most common brain tumor in adults.
• It's a fast-growing cancer that spreads within the brain.
• Symptoms include headaches, seizures, nausea and vomiting, and vision, speech, hearing, and thinking problems.
• You'll see many medical specialists for treatment. Be sure to ask them questions. And if you're facing challenges in your personal life, make sure they know about them.
• Treatment often involves surgery, radiation, and chemotherapy.
• Depression is common with GBM. Don't hesitate to ask for a referral to a psychiatrist or mental health counselor for yourself and family members.
• It's important to continue follow-up after treatment.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you don't take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours and on weekends and holidays.