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Understanding Glioblastoma Multiforme (GBM)

Glioblastoma multiforme (GBM) is a fast-growing cancer that starts in the brain. It’s the most common type of brain cancer in adults.

How a glioblastoma multiforme grows

GBM is a type of brain tumor known as a glioma. It starts in glial cells, which help keep the nerve cells in the brain healthy. Glial cells are a type of brain cell called astrocytomas.

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. These tumors grow quickly and often spread into nearby brain tissue.

What causes glioblastoma multiforme?

Researchers are still learning what causes GBM. Changes in a cell's genes are a key part of cancer. These gene changes affect the way the cells grow. Cancer cells grow and divide out of control to form a tumor. Most gene changes occur randomly, and researchers haven't found a way to keep them from happening.

Symptoms of glioblastoma multiforme

The symptoms of GBM often depend on where the tumor is in the brain. Different parts of the brain control different things. For instance, 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 grows, it increases the pressure in the skull and causes more symptoms.

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

  • Headaches

  • Vision changes

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

  • Nausea or vomiting

  • Seizures

  • Mood swings

  • Personality changes

  • Trouble concentrating

  • Problems with memory

  • Learning difficulties

  • Changes in how you walk and balance problems

Diagnosing glioblastoma multiforme

Your healthcare provider will ask about your health history and your symptoms. A physical exam will be done. 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 specialist to help make the diagnosis. This healthcare provider may be a neurologist or neurosurgeon. These are healthcare providers 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 healthcare providers who treat cancer.

If your healthcare provider thinks you might have a brain tumor, more tests will be needed. These tests can help tell the difference between a tumor and other possible causes of your symptoms, like an infection 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, swelling, bleeding, and signs of stroke. It's the best test to look for GBMs.

  • Magnetic resonance spectroscopy (MRS). This can be done as part of an MRI. It helps look at chemical changes in different parts of the brain.

  • CT scan. This test can help find bleeding in the brain, skull bone changes, and calcium deposits.

  • Needle biopsy. To do this, your provider uses CT or MRI to guide a needle into the tumor so that a tiny piece of it can be taken out and tested for cancer. This is seldom done to diagnose GBM. Instead, surgery is done to take out the tumor and then it's sent for testing.

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

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