Glioblastomas are what’s known as primary brain tumors. That is, they are tumors that originate in the brain. That makes them quite different from metastatic, or secondary, brain tumors, which are tumors that first arise in other organs and then spread to the brain. It’s an important distinction, because primary and secondary brain tumors are treated quite differently.

How Do Glioblastomas Differ From Other Brain Tumors?

Tumors that begin in glial cells, which are cells in the brain that hold nerve cells in place and help them work, are known as gliomas. About 30 percent of all brain tumors are gliomas. They include astrocytomas, oligodendrogliomas, and ependymomas.

Astrocytomas start in glial cells called astrocytes. Glioblastomas are one kind of astrocytoma — the most aggressive kind.

One of the problems with astrocytomas is that they can spread throughout the brain, blending with normal tissue. That makes them almost impossible to remove completely with surgery. While they generally don’t spread to other parts of the body, they can spread through cerebrospinal fluid.

Like other brain tumors, astrocytomas occur in four grades.

Non-Infiltrating (Grade 1) Astrocytomas These do not usually spread into nearby tissues and can be more easily removed surgically. Patients with these tumors often have a good prognosis. These tumors are more common in children than in adults.
Low-Grade (Grade 2) Astrocytomas These can grow slowly into nearby areas and can become more aggressive over time.
Anaplastic (Grade 3) Astrocytomas These grow more quickly and can turn into glioblastomas.
Glioblastomas (Grade 4) This is the stage at which these tumors grow fastest. They are the most common malignant brain tumors in adults.

Causes and Risk Factors for Glioblastoma

Researchers have identified some risk factors for brain tumors, but most tumors have no known cause. Some risk factors are under your control, while others, such as age and a family history of the disease, can’t be changed.

One risk factor for glioblastomas and brain tumors — perhaps the best known and most important — is radiation exposure.

This often arises when radiation is used to treat some other condition. Before the risks were known, children with ringworm on their scalp were treated with low-dose radiation. Tragically, this was later found to increase their risk of brain tumors as they got older — a risk factor that doctors could not undo.

Many people with brain tumors were put at increased risk by radiation therapy used to treat other kinds of cancer. Children whose brains are exposed to radiation to treat leukemia, for example, may develop brain tumors 10 to 15 years later.

Radiation-induced tumors are not common, but doctors now weigh the risks and benefits very carefully before using radiation therapy. Radiation exposure from X-rays or CT scans is much smaller than exposure to radiotherapy, and the risk of brain tumors as a result of these types of scans is believed to be negligible.

How Is Glioblastoma Diagnosed?

There is no simple test to diagnose glioblastoma. Doctors suspect that a brain tumor is a potential diagnosis on the basis of signs and symptoms that generally accompany the illness.

That can be challenging because some of the typical indicators, such as headaches, nausea, and vomiting, are present in other illnesses too.

The person to see for a diagnosis is a neurologist, who will inquire about your symptoms and your history and check such things as your reflexes, balance, and short-term memory. If the neurologist suspects a brain tumor, he or she will refer you for additional tests.

These tests can help the doctor determine if your symptoms are caused by a tumor or something else, such as an infection, abscess, or stroke. Diagnostic tests for glioblastoma can include an MRI, CT scan, magnetic resonance spectroscopy (MRS), needle biopsy, or a blood test.

Prognosis of Glioblastoma

Glioblastomas rarely spread to other parts of the body, but it is a very aggressive cancer with a poor prognosis. It grows quickly inside the brain, destroying brain tissue in the process.

Progress against the disease has been slow. “We haven’t yet been able to find a cure, but we have seen incremental improvements in survival. The median length of survival was only 8 to 10 months in the mid-1990s, but it has almost doubled to 15 to 18 months now,” says Dr. Gilbert.

A small percentage of people do live longer with glioblastoma. A 2019 study analyzed 48,652 cases of glioblastoma to look at the survival rate. Researchers found that 5.5 percent of patients live for five years after diagnosis.

Treatment and Medication Options for Glioblastoma

Glioblastomas have long been a source of frustration for oncologists, who have not been able to treat patients who have this type of cancer nearly as effectively as they would like to. They have made very slow progress at extending the life span of patients with the illness.

Glioblastoma is treated with surgery, radiation, and chemotherapy.

The goal of surgery is to remove as much of the tumor as possible without injuring the brain tissue surrounding it.

Unfortunately, glioblastomas are surrounded by migrating, infiltrating tumor cells that invade surrounding tissues, making it impossible for surgeons to ever remove the tumor entirely.

After surgery and healing of the wound, radiation therapy, in conjunction with drug therapy, usually begins. Studies on radiation therapy show that, on average, people live longer when treated with surgery and radiation therapy than with surgery alone.

Daily doses of temozolomide (Temodar) are usually given along with the radiation. This oral chemotherapy drug makes the tumor more sensitive to radiation, thereby making the combined treatment more effective than radiation alone.

One of the challenges of treating glioblastomas is that the brain has a layer of cells called the blood-brain barrier that blocks entry to substances that could potentially harm the brain. It’s difficult to get certain chemotherapy drugs past that wall.

Medication Options

In some cases, a targeted drug therapy called bevacizumab (Avastin) is used to treat glioblastoma. The medication is given intravenously to stop the formation of new blood vessels, thereby cutting off blood supply to a tumor and killing the tumor cells.

Polifesrosan 20 with carmustine (Gliadel) implant is an FDA-approved drug sometimes used as an adjunct to surgery to extend life in patients with recurrent glioblastoma who undergo surgery.

Experimental Therapies May Aid Glioblastoma Survival

There are two main experimental approaches to developing better treatments for glioblastoma.

One is the use of immunotherapy — a strategy now being used for many kinds of cancer. These treatments manipulate the body’s immune system to boost its ability to recognize, attack, and kill tumor cells. The other approach is to directly target the tumor cells, specifically the cell signaling pathways that control cell growth and which have gone haywire as a result of genetic mutations.

Researchers are also developing better ways to image tumors so that surgeons can remove as many of the tumor cells as possible. The lingering cells that surgeons inevitably miss give rise to further tumor growth. The more of the tumor that surgeons can catch, the better the outlook is likely to be for the patient.

Alternative and Complementary Therapies

There is very little research on alternative or complementary treatments for glioblastoma. To date, there are no alternative therapies that are proven to help in the treatment of glioblastomas.

Complementary treatments can help people cope throughout treatment and beyond. They include the following:

Acupuncture
Hypnosis
Meditation
Music therapy
Relaxation exercises

It’s important to talk to your doctor first before taking any vitamins, herbs, or nutritional therapies to address issues or side effects related to cancer or its treatment.

Complications of Glioblastoma

If glioblastoma isn’t treated, it can continue to grow and spread throughout the brain. This can cause ongoing functional loss and greater pressure within the skull, worsening some symptoms like seizures, personality changes, problems speaking, and loss of memory.

If treated with surgery, radiation, and chemotherapy, complications may include depression, recurrence of the cancer, and side effects of medications used in treatment.

Chemotherapy can increase the risk of infection or bleeding, and surgery and radiation can cause changes in brain function.

Steroids are sometimes used to ease brain swelling and can cause insomnia, increased risk of infection, weight gain, and mood changes.

Glioblastoma Resources We Love

When you’re coping with any kind of cancer, you’ll want to identify organizations that can provide information and assistance for you and your family. There are a wide range of organizations available to help with information, support groups, and even getting to appointments.

National Cancer Institute: Brain Tumors — Patient Version

Sponsored by the National Cancer Institute, this website provides comprehensive information about all aspects of brain cancer as well as the latest research.

About Brain and Spinal Cord Tumors in Adults

This valuable resource provided by the American Cancer Society covers what you need to know if you or a loved one is diagnosed with glioblastoma, and it includes information on the basics, such as the parts of the brain and different kinds of tumors.

Toward the End of Life: What You and Your Family Can Expect

A diagnosis of glioblastoma can be incredibly difficult. There are many decisions that individuals and families need to make about treatment. This guide provided by Memorial Sloan Kettering Cancer Center gives an overview of what to expect toward the end of life.

ClinicalTrials.gov

Maintained by the U.S. National Library of Medicine, this database keeps track of the clinical trials that are underway or are recruiting patients and is searchable by condition or disease.

Additional reporting by Becky Upham.

Editorial Sources and Fact-Checking

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