The recent passing of Senator John McCain has put glioblastoma multiforme, the most common form of brain cancer in adults, in the spotlight. (Senator McCain was diagnosed with glioblastoma in 2017, and passed away on August 25, 2018, at the age of 81.) According to estimates from the American Brain Tumor Association, nearly 13,000 people will be diagnosed with glioblastoma this year. For those wishing to learn more about the disease, the online health library of Cedars-Sinai Medical Center offers a helpful fact sheet, including answers to the following frequently asked questions:

What is glioblastoma multiforme?

Glioblastoma multiforme (GBM) is a type of brain tumor that develops from cells known as astrocytes. Astrocytes assist in the formation of the blood-brain barrier, a kind of “gatekeeper” for the brain that allows certain substances to pass into the brain while preventing other substances from entering. Astrocytes also provide support and deliver nutrients to vital nerve cells. When a tumor, like GBM, develops from astrocytes, it is known as an astrocytoma.

In addition to being the most common type of brain tumor to affect adults — about 60 percent of so-called primary brain tumors are cases of GBM — GBM is also one of the most aggressive. Ranked as a grade IV astrocytoma (for brain tumors, grade I is the least aggressive, with grade IV being the most), GBM grows quickly, and it is common for them to spread into nearby brain tissue. These tumors can affect adults of any age, but they occur most often between the ages of 45 and 70. The median survival for people with GBM is 24 months.

What causes GBM?

The causes of GBM are still not clear. Astrocytes are cells that are typically very controlled and organized, and we simply do not know what causes them to begin multiplying and forming the disorganized sheets of cells that develop into a tumor. GBMs usually appear in the brain spontaneously with no clear associated risk factors, although experts estimate that about 5 percent of cases may have a genetic component. While most GBMs start as glioblastomas, in rare cases, a lower-grade tumor will transform into a GBM.

What are the symptoms of a GBM?

Because GBM affects the brain, some symptoms of the disease may be related to the specific location of the tumor. For example, if a GBM develops in the area of the brain that controls arm movements, the arm may become weak or have difficulty functioning.

In general, many GBM symptoms develop gradually and worsen as the tumor grows and takes up more space, putting more pressure on the brain. Common symptoms can include headaches; problems with memory or concentration; fatigue and weakness; mood swings and personality changes; loss of appetite; nausea or vomiting; problems with speech; changes in vision; and seizures.

How is GBM diagnosed?

A visit to a doctor or primary healthcare provider is usually the first step for people experiencing any of the symptoms described above. Typically, the doctor will take a full medical history, including asking about recent symptoms, and will conduct an exam to evaluate vision, hearing, strength, and reflexes. The doctor may ask precise questions to help assess memory and learning ability, as well as have the person walk or move around to check coordination and balance.

If the physician suspects a brain tumor, more tests will be required. This stage of testing helps determine whether factors other than a brain tumor — such as infections, abscesses, or strokes — could be causing the symptoms. Typically, a specialist like a neurologist, a neurosurgeon, or an oncologist will help conduct the tests and make the diagnosis. Tests may include the following:

Magnetic resonance imaging, or MRI — A radiological imaging technique; MRI can not only reveal tumors, but also areas of swelling, blood, and areas that have been affected by a stroke.

Computed tomography scan, or CT scan — Uses a combination of X-rays and computer imaging to create pictures of organs, bones, and tissues. CT scans can help identify areas of fresh bleeding, abnormalities in the skull, and calcium deposits.

Magnetic resonance spectroscopy, or MRS — Often performed as part of an MRI, MRS can help examine and evaluate the various chemical processes happening in different areas of the brain.

A needle biopsy — This test involves taking a sample of tissue for microscopic examination.

How is GBM treated?

GBM treatments usually require the coordinated efforts of doctors from multiple specialties and other medical personnel including nurses, social workers, and occupational or physical therapists. However, specific treatment plans can vary greatly depending on a patient’s age, overall state of health, personal preferences for treatment, and the tumor’s size and location. Sometimes, treatment for GBM can be aggressive, involving surgery, radiation, and chemotherapy; in other cases, people choose to receive palliative care only to maximize their quality of life without actively treating the tumor. In addition, research and clinical trials are underway on a number of experimental treatment options, including cancer vaccines, gene therapy, and highly focused radiation therapy.