The words glioma and glioblastoma may look alike, and even sound alike, but the truth is more complicated.
“Glioma is a large category that includes a number of different types of tumors,” explains Lindsay Lipinski, MD, MS, FAANS, Associate Professor of Neurosurgery and Oncology at Roswell Park Comprehensive Cancer Center. The word “glia” means glue and glial cells are the ones that hold everything together in the brain by providing a framework to support and nourish the actual nerve cells which are also known as neurons.
Gliomas are graded on a scale of one to four. Grade one gliomas usually grow slowly and frequently behave in a more benign fashion. Grade two and grade three gliomas can grow more quickly and they frequently require more aggressive treatment. Grade four gliomas are the most aggressive type. This category includes glioblastoma (formerly called globlastoma multiforme, or GBM for short) and Grade four astrocytomas.
“Lower grade gliomas typically occur in younger patients,” Dr. Lipinski says. “They can present with seizures and less commonly with neurological deficits such as weakness or speech problems.” Sometimes lower-grade gliomas (grades one and two) can be found incidentally in patients who have an MRI or CT scan performed for a different reason, such as for migraines or minor head injury.
Most gliomas will require asurgery for tissue testing to determine their grade and to predict their future behavior and growth rate. Grade one gliomas may be treatable with surgery alone and then monitored for regrowth without further treatment. However, grades two and three gliomas usually require additional treatment, which may include some combination of surgery, radiation therapy, and chemotherapy or targeted therapy. These gliomas can recur even with treatment, and occasionally can progress to a higher grade over time.
“Generally, the treatment for glioblastomas and Grade four astrocytomas must be more aggressive because we know that its behavior involves fairly rapid growth. Watching and waiting doesn’t play a role,” Dr. Lipinski says. “We want a tissue diagnosis as soon as possible, either through a biopsy or removal of the tumor, and then chemotherapy and radiation must start pretty shortly after that.”
Identifying and typing a glioma
“Gliomas are typically seen well on a brain MRI scan,” Dr. Lipinski says, with MRI scans being much better than CT scans for seeing these tumors clearly.
In addition to the one-to-four grading system, gliomas are also classified based on the type of glial cell from which they develop. Glial cells that give rise to tumors in the brain can include ependymal cells (ependymomas), astrocytes (astrocytomas) and oligodendrocytes (oligodendrogliomas). Ependymal cells line the brain’s ventricles where spinal fluid is contained. Astrocytes provide the structural framework of the brain. Oligodendrocytes create the myelin sheath for the neurons that acts a little like insulation for wires throughout the brain’s communication system. Oligodendrogliomas frequently have a better prognosis, even at higher grades, and people diagnosed with oligodendroglioma tend to have a longer survival rate than patients with astrocytomas.
With advancements in molecular testing and genetic sequencing, we are able to gain additional information about tumor diagnosis and treatment options. This type of testing also plays in important role in assigning a grade to a glioma.
“Most gliomas are locally invasive but it is very uncommon for any glioma to metastasize outside of the nervous system to other organs,” Dr. Lipinski says. "It’s also uncommon for gliomas to run in families. The great majority of gliomas are sporadic, meaning there is no family history, but patients who have an inherited cancer predisposition syndrome may be at higher risk."
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Don’t jump to conclusions about headaches
Dr. Lipinski stresses that headaches are rarely an indication of a brain tumor and that other causes like migraine are far more common.
“There are no real screening tests for glioma. For most patients, diagnosis is reliant upon someone having neurologic symptoms,” Dr. Lipinski says. “That could include having a seizure or developing weakness, numbness, speech problems, partial loss of vision or impaired thinking. Lots of times, people with brain tumors come to an emergency room with stroke-like symptoms but it’s only when you get ascan MRI or CT scan that the medical team realizes it’s a tumor, not a stroke.”
Anyone diagnosed with a glioma is encouraged to follow the advice of their physician and understand that “not every situation is an emergency,” she adds. “There’s often time to get a second opinion.”
