When you hear the word "glioma," it can feel like the ground has been pulled out from under you. Medical terminology can make an already overwhelming situation even harder to navigate. This guide breaks down what gliomas are, the different types, how they are treated, and where to find support — in plain language.
The Sean Ryan Foundation was founded after Sean Ryan lost his battle with a histone mutated diffuse midline glioma (DMG) in 2023. We share this information because understanding your diagnosis is the first step toward fighting it.
What Is a Glioma?
A glioma is a tumor that grows from glial cells — the supportive cells in the brain and spinal cord that surround and protect neurons. Gliomas are the most common type of primary brain tumor, accounting for about 33% of all brain tumors.
Gliomas are classified by:
- Cell type — which kind of glial cell the tumor developed from
- Grade — how aggressive the tumor appears under a microscope (Grades 1 through 4)
- Molecular markers — genetic characteristics of the tumor that affect treatment and prognosis
The World Health Organization (WHO) updated its brain tumor classification system in 2021, placing greater emphasis on molecular markers alongside traditional grading. This means two tumors that look similar under a microscope may be classified differently based on their genetic profile.
Common Types of Gliomas
Glioblastoma (GBM) — WHO Grade 4
Glioblastoma is the most common and most aggressive malignant brain tumor in adults. It grows quickly and tends to infiltrate surrounding brain tissue, making complete surgical removal extremely difficult.
- Who it affects: Most commonly diagnosed in adults ages 45 to 70
- Standard treatment: Surgery (when possible), followed by radiation and temozolomide chemotherapy — known as the Stupp protocol
- Key molecular marker: IDH-wildtype status (distinguishes it from lower-grade gliomas that have transformed)
Astrocytoma — WHO Grades 2, 3, or 4
Astrocytomas develop from star-shaped glial cells called astrocytes. They range from slow-growing (Grade 2) to highly aggressive (Grade 4).
- Grade 2 (low-grade): Slow growing but can progress over time. May be monitored or treated with surgery.
- Grade 3 (anaplastic): More aggressive, typically requiring surgery, radiation, and chemotherapy.
- Grade 4: Functionally similar to glioblastoma in aggressiveness.
- Key molecular marker: IDH-mutant astrocytomas generally have a better prognosis than IDH-wildtype tumors.
Oligodendroglioma — WHO Grades 2 or 3
Oligodendrogliomas develop from oligodendrocytes, the cells that produce the protective myelin coating around nerve fibers.
- Who it affects: More common in adults ages 30 to 50
- Distinguishing feature: These tumors have a characteristic molecular signature — IDH mutation plus 1p/19q co-deletion — which is associated with better response to treatment
- Treatment: Surgery followed by radiation and chemotherapy (often PCV: procarbazine, CCNU, and vincristine)
- Prognosis: Generally more favorable than other gliomas, with many patients living years to decades with treatment
Diffuse Midline Glioma (DMG) — WHO Grade 4
Diffuse midline gliomas occur in midline structures of the brain, including the brainstem (where they were historically called DIPG), thalamus, and spinal cord.
- Who it affects: Most common in children, but also occurs in adults. Sean Ryan was diagnosed with a histone mutated DMG at age 36.
- Key molecular marker: H3 K27-altered (a histone mutation)
- Treatment challenges: Location often makes surgery impossible. Standard treatment is radiation therapy, but clinical trials are actively exploring new approaches.
- Research focus: DMG is an area of intense research, with promising work in immunotherapy and targeted molecular therapies.
Ependymoma — WHO Grades 1, 2, or 3
Ependymomas develop from ependymal cells that line the ventricles (fluid-filled spaces) in the brain and the central canal of the spinal cord.
- Who it affects: Can occur at any age, including children
- Treatment: Surgery is the primary treatment, sometimes followed by radiation
- Prognosis: Varies significantly based on location, grade, and extent of surgical removal
How Gliomas Are Diagnosed
Diagnosis typically involves:
- Neurological exam — testing vision, hearing, balance, coordination, strength, and reflexes
- MRI with contrast — the primary imaging tool for brain tumors. Shows tumor size, location, and characteristics.
- Biopsy or surgery — a tissue sample is examined under a microscope and tested for molecular markers. This is the only way to confirm the exact tumor type and grade.
- Molecular testing — labs test for specific genetic markers (IDH mutation, 1p/19q co-deletion, MGMT methylation, H3 alterations) that guide treatment decisions
Treatment Approaches
Surgery
The goal is to remove as much tumor as safely possible without damaging critical brain functions. Advanced techniques include:
- Awake craniotomy — the patient is awake during parts of the surgery so the surgeon can test brain function in real time
- Fluorescence-guided surgery — a special dye makes tumor cells glow, helping the surgeon distinguish tumor from healthy tissue
- Intraoperative MRI — real-time imaging during surgery to maximize tumor removal
Radiation Therapy
Radiation uses high-energy beams to target and destroy tumor cells. Common approaches include:
- External beam radiation — the standard approach, usually given daily for 5 to 6 weeks
- Stereotactic radiosurgery (Gamma Knife, CyberKnife) — highly focused radiation delivered in fewer sessions. Sean Ryan underwent a Gamma Knife procedure at the University of Minnesota.
- Proton therapy — uses protons instead of X-rays, potentially reducing damage to surrounding tissue
Chemotherapy
- Temozolomide (Temodar) — the most commonly used chemotherapy for gliomas, taken orally
- PCV (procarbazine, CCNU, vincristine) — often used for oligodendrogliomas
- Bevacizumab (Avastin) — used for recurrent glioblastoma to reduce swelling and slow growth
Clinical Trials
Clinical trials test new treatments that are not yet widely available. They represent the cutting edge of brain cancer research and may offer options when standard treatments are insufficient.
- Ask your neuro-oncologist about trials you may qualify for
- Search for trials at clinicaltrials.gov using your specific tumor type
- Major cancer centers often have the most trial options available
Emerging Therapies
Research is advancing rapidly in several areas:
- Immunotherapy — training the immune system to recognize and attack tumor cells
- Tumor treating fields (TTFields/Optune) — a wearable device that uses electric fields to disrupt tumor cell division
- Targeted molecular therapy — drugs designed to attack specific genetic vulnerabilities in the tumor
- CAR-T cell therapy — genetically modified immune cells that target brain tumor cells, showing early promise in clinical trials
Living with a Glioma
A glioma diagnosis is not just a medical event — it reshapes daily life:
- Cognitive changes — some patients experience difficulties with memory, concentration, or language. Neuropsychological testing can identify specific challenges, and cognitive rehabilitation can help.
- Seizures — brain tumors can cause seizures. Anti-seizure medications are commonly prescribed, and most patients achieve good seizure control.
- Fatigue — treatment-related fatigue is real and significant. Rest is not laziness — it is a medical necessity.
- Driving — many patients are temporarily restricted from driving, especially if they have had seizures. Discuss this with your medical team.
- Work — some patients continue working with accommodations, while others are unable to. Know your rights under the ADA and explore FMLA and disability options early.
Finding Support
You do not have to navigate this alone:
- The Sean Ryan Foundation — we provide direct financial assistance and community support to families affected by brain cancer. If you or someone you know is fighting a glioma, reach out to us.
- Hospital support groups — many cancer centers have brain tumor-specific support groups
- Online communities — forums and social media groups connect patients and caregivers facing similar diagnoses
- Oncology social workers — trained professionals who can help with everything from insurance navigation to emotional support
This article is for educational purposes and does not constitute medical advice. Brain tumor classification and treatment are complex and evolving — always consult with your neuro-oncology team for guidance specific to your diagnosis. The Sean Ryan Foundation is a registered 501(c)(3) nonprofit.