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Glioblastoma

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was reviewed on June 8, 2022.

Glioblastoma is a form of brain cancer that grows and spreads very quickly. Treatments are designed to slow down its growth and help relieve symptoms.

What is glioblastoma?

Glioblastoma, also called glioblastoma multiforme or GBM, starts in brain cells called glial cells. Specifically, it starts in the star-shaped glial cells known as astrocytes. Astrocytes help the nerve cells in your brain develop and function properly.

According to the National Cancer Institute, glioblastomas are the most common type of brain tumor in adults, accounting for at least 35 to 40 percent of all cancerous brain tumors. About 14,000 people are diagnosed with glioblastoma every year. Men get glioblastomas more often than women. Most people who are diagnosed are older, between ages 45 and 70, but people of any age can develop glioblastoma.

Glioblastoma causes and risk factors

Scientists don’t know what causes glioblastoma. Although they haven’t discovered a single risk factor, glioblastoma has been associated with:

  • Previous treatment with radiation therapy 
  • Some genetic (hereditary) conditions that cause tumors, including Lynch, Turcot and Li-Fraumeni syndromes, and neurofibromatosis type 1 (NF1). Although people with these syndromes do sometimes develop glioblastoma, it’s rare. Glioblastoma itself isn’t considered hereditary.
  • Exposure to certain toxic chemicals

Learn more about brain cancer causes and risk factors

Glioblastoma symptoms

Glioblastomas can grow anywhere in the brain. The rapid growth of the tumor can put pressure on the brain and cause the following symptoms, which are typically worse in the morning:

Where a tumor is located in the brain can determine what kind of effects it has, such as:

Other symptoms may include:

  • Seizures
  • Mood or personality changes
  • Vision problems
  • Speech problems that gradually get worse

Symptoms may come on suddenly or slowly get worse.

How glioblastomas are diagnosed

Your care team will use various imaging techniques, such as magnetic resonance imaging (MRI) or a computed tomography (CT) scan (also called a CAT scan), to take pictures of your brain and look for a tumor.

MRI

An MRI machine uses radio waves and magnets to create images of the brain. You may have an MRI without contrast or an MRI with contrast, which means the nurse or technician who does the MRI injects a contrast dye into your arm. This helps show the location of the tumor as a bright area on the scan.

Your doctor may want you to have other kinds of MRI tests, called functional MRI (fMRI) and MRI spectroscopy (MRS).

  • A functional MRI shows what sections of your brain are threatened by the tumor and can help in planning surgery to remove the tumor. During an fMRI, you’ll be asked to do certain tasks such as raising your arm or speaking, while the imaging screen shows which area of your brain is active.
  • MRI spectroscopy can help doctors find out more about a suspected tumor without doing a biopsy. MRS can show levels of different chemicals in your brain that might indicate whether a tumor is present.

CT scan

CT scans use X-rays to produce three-dimensional images that can evaluate a tumor’s size. They can also show any bleeding or enlargement of the fluid-filled ventricles in your brain. Some CT scans use a contrast medium, which may be taken by mouth or injected into a vein.

If a tumor is found, you may have a biopsy, which takes a small amount of tissue from the tumor so it can be analyzed to see what kinds of cells are present and how aggressive the tumor is. Glioblastoma is hard to treat, and this information may help your doctor decide which treatments may work best for your particular tumor.

Grading

Doctors use a grading system for brain tumors that indicate how fast they grow. Grade IV is the highest grade and has the most challenging course. All glioblastomas are considered grade IV, which means they grow quickly and are very aggressive.

Glioblastoma treatment

Because glioblastomas are difficult to treat, treatments are designed to help you live longer, have fewer symptoms and better quality of life. Treatment includes surgery, followed by radiation therapy and chemotherapy.

The goal of surgery is to remove as much of the tumor as possible without harming the rest of the brain. Because of the way glioblastomas grow, with cancer cells extending into normal brain tissue, it’s difficult if not impossible to remove all the cancer cells. However, surgery reduces pressure inside the skull, which may help lessen symptoms. It may also remove the parts of the tumor that are more resistant to radiation therapy and chemotherapy.

After you’ve recovered from surgery, you may undergo radiation therapy to kill remaining cancer cells. External radiation therapy uses a machine that aims high-energy beams at the site of the tumor and the surrounding area. These treatments may be delivered once daily, five days a week, for two to six weeks. Radiation therapy does cause some damage to healthy tissue, but it may help lengthen survival. Another form of radiation therapy, called radiosurgery, may be used on glioblastoma that starts growing again. This kind of radiation focuses tightly on the tumor so it causes less damage to healthy tissue.

You may undergo chemotherapy along with radiation. You may take the drug temozolomide daily during radiation therapy, then continue taking it in 28-day cycles after radiation is finished. During each cycle, there will be certain days when you take the drug and other days when your body rests and recovers.

A technique called tumor treating fields (TTF) uses electrical fields to slow down the growth of cancer cells. You wear a battery-powered device that creates the fields. TTF may be used with temozolomide after initial radiation therapy. It may cause some skin irritation.

Other forms of chemotherapy, immunotherapy and targeted therapy may be used to slow your cancer’s progression after initial treatment. Your doctor may also suggest that you participate in a clinical trial of a new drug or therapy that’s being studied. Clinical trials test and refine new treatments. They can give patients access to experimental treatments that may become standard in the future.

Glioblastoma treatment

Because glioblastomas are difficult to treat, treatments are designed to help you live longer, have fewer symptoms and better quality of life. Treatment includes surgery, followed by radiation therapy and chemotherapy.

The goal of surgery is to remove as much of the tumor as possible without harming the rest of the brain. Because of the way glioblastomas grow, with cancer cells extending into normal brain tissue, it’s difficult if not impossible to remove all the cancer cells. However, surgery reduces pressure inside the skull, which may help lessen symptoms. It may also remove the parts of the tumor that are more resistant to radiation therapy and chemotherapy.

After you’ve recovered from surgery, you may undergo radiation therapy to kill remaining cancer cells. External radiation therapy uses a machine that aims high-energy beams at the site of the tumor and the surrounding area. These treatments may be delivered once daily, five days a week, for two to six weeks. Radiation therapy does cause some damage to healthy tissue, but it may help lengthen survival. Another form of radiation therapy, called radiosurgery, may be used on glioblastoma that starts growing again. This kind of radiation focuses tightly on the tumor so it causes less damage to healthy tissue.

You may undergo chemotherapy along with radiation. You may take the drug temozolomide daily during radiation therapy, then continue taking it in 28-day cycles after radiation is finished. During each cycle, there will be certain days when you take the drug and other days when your body rests and recovers.

A technique called tumor treating fields (TTF) uses electrical fields to slow down the growth of cancer cells. You wear a battery-powered device that creates the fields. TTF may be used with temozolomide after initial radiation therapy. It may cause some skin irritation.

Other forms of chemotherapy, immunotherapy and targeted therapy may be used to slow your cancer’s progression after initial treatment. Your doctor may also suggest that you participate in a clinical trial of a new drug or therapy that’s being studied. Clinical trials test and refine new treatments. They can give patients access to experimental treatments that may become standard in the future.

Glioblastoma signs of decline

Because glioblastoma is difficult to treat, your symptoms will eventually get worse. You may be sleepy and spend more time sleeping, and you may have headaches and nausea. It’ll get harder to move and speak, and you may have problems swallowing or seeing. Some people experience mood and personality changes. Talk to your cancer team about palliative care, which helps manage symptoms and ease discomfort. You can receive palliative care while you are receiving other treatment, such as chemotherapy and radiation therapy.

Glioblastoma survival rate

While overall survival rates from glioblastoma are low, each patient is different and many factors influence how long someone survives with glioblastoma. For example, the American Cancer Society (ACS) notes that the five-year relative survival rates for glioblastoma patients can vary by age:

  • 22 percent for people aged 20 to 44
  • 9 percent for people aged 45 to 54
  • 6 percent for people aged 55 to 64

Researchers continue to study new treatments that may help patients live longer. According to the National Cancer Institute, the average time of survival after glioblastoma diagnosis was eight to 10 months in the 1990s, but it’s now almost twice as long at 15 to 18 months. Overall, 15 percent of people are still alive five years after diagnosis.

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