Understanding Glioblastoma Multiforme (GBM)

Glioblastoma multiforme (GBM) is a fast-growing brain tumor. It’s the most common type of brain cancer tumor in adults. GBMs occur most often in adults ages 45 to 70.

How a glioblastoma multiforme grows

GBM is a type of brain tumor known as a glioma. It grows from cells in the brain that help keep the nerve cells in the brain healthy. Brain tumors are graded on a 1 to 4 (I to IV) scale based on how fast they grow. Grade I brain tumors grow the slowest. Grade IV tumors grow the fastest. GBMs are grade IV astrocytomas. (Astrocytomas are a type of brain cell. GBM most commonly starts in these cells.) They grow quickly and often spread into nearby brain tissue.

What causes glioblastoma multiforme?

Researchers are still learning what causes GBM. Changes in genes are part of the cause. These changes may affect the ability of the cells to grow normally. Most of these changes occur randomly, so researchers haven't found a way to keep them from happening.

Symptoms of glioblastoma multiforme

Some of the symptoms of GBM are based on where the tumor is growing in the brain. Different parts of the brain control different things. For example, if a GBM 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 increases the pressure in the skull and causes more symptoms.

GBM symptoms often start slowly and get worse over time. They may include:

  • Headaches

  • Vision changes

  • Sensation changes

  • Trouble or changes with how you talk, see, and hear

  • Weakness

  • Nausea or vomiting

  • Loss of appetite

  • Seizures

  • Tiredness

  • Mood swings

  • Personality changes

  • Trouble concentrating

  • Problems with memory

  • Learning difficulties

  • Changes in how you walk

Diagnosing glioblastoma multiforme

Your healthcare provider will ask about your health history and your symptoms. He or she will give you an exam. This will include checking your vision and hearing, strength, reflexes, and sense of touch. You may be asked questions to check your memory and learning ability. You may be asked to walk around. This is to check your gait, coordination, and balance.

Your provider will likely refer you to a special doctor to help make the diagnosis. This doctor may be a neurologist or neurosurgeon. These are doctors who specialize in treating diseases of the brain. If you have a tumor, you may also see an oncologist or neuro-oncologist to help plan your treatment. These are doctors who treat cancer.

If your doctor thinks you might have a brain tumor, you will need more tests. These tests can help tell the difference between a tumor and other possible causes of your symptoms, such as an infection, abscess, or stroke. The tests will also help find out if a brain tumor is cancer. Tests used may include:

  • MRI. This test can help find tumors, areas of swelling, blood, and areas affected by stroke.

  • CT scan. This test can help find areas of bleeding, skull abnormalities, and calcium deposits.

  • Magnetic resonance spectroscopy (MRS). This test can help look at chemical processes happening in different parts of the brain.

  • Needle biopsy. This test uses CT or MRI to guide the provider to the tumor so that a tiny piece of the tissue can be taken out and checked under the microscope.

  • Blood tests. These look for signs of infection or diseases and give a sense of your overall health.