Behind the Tumor: Glioblastoma (GBM)

Types

Healthcare providers use a grading system from 1 to 4 to indicate brain tumor growth. Grade 1 brain tumors grow slowly and are the least aggressive. Grade 4 tumors grow rapidly and are more aggressive.

GBMs are grade 4 by definition. If your tumor has a mutation in IDH (isocitrate dehydrogenase) then it is called an IDH-mutant tumor, which can also be a grade 4 but has grown more slowly and behaves a
bit better.

Location

Glioblastoma can start anywhere in the brain. The area near the forehead is the frontal lobe. It plays important roles in speech, voluntary movement, behavior, and memory. The temporal lobe creates new memories, processes language, and processes input from the senses of hearing, sight, taste, and touch.  The parietal lobes help with sense of touch and processing sight and sound, and the occipital lobe helps with interpreting visual information.

Population

GBM commonly affects people ages 45 to 70. The average age at diagnosis is 64. Men have a slightly higher risk, but the disease affects all ages and genders.

These factors may increase your risk:

• Exposure to chemicals, such as pesticides, petroleum, synthetic rubber and vinyl chloride.
• Genetic, tumor-causing conditions, such as neurofibromatosis, Li-Fraumeni syndrome and Turcot syndrome.
• Previous radiation therapy to the head.

Symptoms

GBM symptoms tend to come on quickly. The growing tumor puts pressure on the brain, causing:

• Blurred or double vision.
• Headaches.
• Loss of appetite.
• Memory problems.
• Mood or personality changes.
• Muscle weakness or balance problems.
• Nausea and vomiting.
• Seizures.
• Speech problems.
• Changes in sensation, numbness or tingling.

Treatment

Glioblastomas can be difficult to treat for the following reasons:

• They are fast-growing and invade nearby brain tissue, making 100% removal nearly impossible.
• The blood-brain barrier prevents certain treatments from being able to reach the tumor and be effective.
• They have many different types of tumor cells (heterogeneous) and can change over time, which makes them difficult to treat.

Glioblastoma surgery

Glioblastoma surgery is most successful when it’s performed by a neurosurgeon with extensive experience in brain tumor surgery. There are a number of different surgical options for people with glioblastoma. Your physician will evaluate your case and discuss the best one for you.

Craniotomy

Craniotomies are the standard surgery for most brain tumors, including glioblastoma. Surgeons performing a craniotomy remove a section of the skull in order to access the tumor.

Awake craniotomy

One advanced type of surgery is the awake craniotomy. This procedure is performed on patients whose tumor is located in a part of the brain that controls essential functions. During an awake craniotomy, doctors wake up the patient during the procedure. They can then interact with the patient to map the location of key areas of the brain. This lets the neurosurgeon avoid those functional areas during surgery while removing as much of the tumor as safely as possible. Because of local anesthesia and the brain’s lack of pain receptors, patients don’t feel any pain during the operation.

Laser interstitial thermal therapy

This treatment, also known as LITT, is primarily used to treat tumors that are difficult to reach with standard surgical techniques. During the procedure, neurosurgeons use an intraoperative MRI in an advanced operating room called the BrainSuite® to guide a small laser catheter to the tumor site. There, the laser heats the tumor, killing cancerous cells from the inside while minimizing damage to nearby healthy brain cells.

Radiation therapy for glioblastoma

Radiation therapy uses focused, high-energy beams to kill tumors or tumor sections that cannot be removed with surgery.  Each radiation plan is designed to have the maximum impact on the patient’s tumor while minimizing the effect on healthy brain tissue. The different radiation therapies used to treat glioblastoma are described below. Your radiation oncologist will evaluate your condition and recommend the one that is best for you.

3D conformal radiation therapy for glioblastoma

This technique uses three-dimensional scans to determine the exact shape and size of the tumor. Tiny metal leaves inside the treatment machine, called a linear accelerator, are used to shape the radiation beams. These beams are designed to match the size and shape of the tumor, which minimizes radiation exposure to nearby healthy tissue.

Intensity modulated radiation therapy (IMRT) for glioblastoma

IMRT focuses multiple beams of radiation with different intensity levels directly on the tumor, delivering the highest possible dose of radiation. Radiation oncologists use special software to develop highly-targeted radiation treatment plans for each patient that minimizes the impact on healthy tissues near the tumor.

Proton therapy for glioblastoma

Proton therapy is a specialized form of radiation therapy that delivers high doses of energy directly to the tumor site, with minimal impact on healthy tissue. It is only available at a few centers in the world and is often used to treat tumors located in very sensitive areas of the brain. Proton therapy is currently considered experimental for glioblastoma and is frequently therefore not covered by insurance.

Stereotactic radiosurgery for glioblastoma

Stereotactic radiosurgery (SRS) is a non-invasive treatment that uses dozens of tiny radiation beams to accurately target brain tumors with a single high dose of radiation. Despite its name, SRS is not a surgical procedure and does not require an incision or anesthesia. This technique is typically used for patients whose tumors have recurred and who have already received standard radiation treatments.

Chemotherapy for glioblastoma

Chemotherapies are drugs that kill fast-growing cells, including cancer cells. Chemotherapy can be difficult to deliver to the brain because of the blood-brain barrier, a set of small blood vessels and brain cells that protect the brain from disease, but also act as a shield against chemotherapy drugs.

Medical Device for GBM

The Optune device by Novocure is a treatment that requires patients to shave their heads and wear an adhesive skull cap with wires attached to a battery pack for up to 18 hours a day. During these hours, the device emits radio waves into the brain in order to slow or stop tumor cells from multiplying.

Glioblastoma clinical trials

Because glioblastoma is difficult to treat, doctors are constantly searching for new ways to fight the disease. Some trials study entirely new treatments, while others look at new combinations of existing treatments that may benefit patients. Many use personalized approaches designed around the specific features of a patient’s cancer.

These include trials of surgeries, chemotherapies and radiation therapies. Doctors are also working to bring the latest breakthroughs in cancer care to glioblastoma treatments, including new targeted therapies and immunotherapies. 

Recurrent glioblastoma treatment

Because it is impossible to remove or destroy all glioblastoma cells in a tumor, all glioblastomas recur. The timing can range from weeks to years.

Some patients with recurrent glioblastoma may be eligible for another surgery or LITT to remove as much of the tumor as possible. Radiation therapy can also be used as a palliative measure to slow tumor progression and to relieve symptoms caused by the tumor.

However, many standard treatments haven’t proven effective for recurrent glioblastoma. Patients should work with their care team to consider available treatment options and choose a plan that meets their goals. Many clinical trials are available for recurrent glioblastoma, and you should ask about trial
options at your hospital and elsewhere.

Questions To Ask Your Doctor

It may be helpful to ask your healthcare team the following questions:

• Why did I get glioblastoma?  Might I have a hereditary cause?
• What is the best treatment for me?
• What are the treatment risks and side effects?
• What type of follow-up care do I need after treatment?
• What are the chances that the cancer will come back or spread after treatment?
• Should I look out for signs of complications? 
• What is palliative care and how can they help me and my family?