Understanding Gliomas: What Different Types Mean for Your Diagnosis & Your Treatment Choices

“Neurons don’t proliferate [reproduce rapidly]. Glial cells can. They usually quit by adolescence, but they can start proliferating again later in life. When they proliferate out of control, they will form a tumor on the glial cell we call a glioma,” Dr. Nabors adds.

Understanding Glioma Grading

Unlike many other cancers, which are staged based on tumor spread, gliomas are graded based on their appearance under a microscope and their biological behavior.

Pathologists examine glioma cells for several key characteristics to determine the tumor’s grade.

This analysis includes:

• Cell Appearance: The more abnormal the tumor cells look, the higher the grade.
• Cell Division: A higher number of actively dividing cells suggests faster tumor growth.
• Vessel Formation: The presence of new blood vessels feeding the tumor indicates a more aggressive glioma.
• Necrosis: Dead tumor cells signal highly aggressive tumor behavior.

Gliomas are graded on a scale from 1 to 4, with higher grades indicating greater aggressiveness.

What Does Grade Mean for Treatment?

1. Grade 1 Gliomas (Low-Grade, Least Aggressive): These tumors grow slowly and are most common in children. Pilocytic astrocytomas fall into this category. If complete surgical removal is possible, it can often be curative, meaning no further treatment is needed. Patients who undergo successful surgery have an excellent long-term outlook.
2. Grade 2 Gliomas (Low-Grade but More Complex): These tumors also grow slowly but can evolve into higher-grade gliomas over time. Surgery is the primary approach, but some cases may require radiation or chemotherapy if the tumor cannot be fully removed or if it shows signs of progression. Outcomes vary, but regular monitoring is essential to detect potential progression.
3. Grade 3 Gliomas (High-Grade, More Aggressive): These tumors grow more rapidly and are considered malignant. A combination of surgery, radiation, and chemotherapy is often required. Treatment aims to slow progression, but recurrence is common.
4. Grade 4 Gliomas (Glioblastomas – Most Aggressive): These fast-growing tumors infiltrate surrounding brain tissue and are the most aggressive form of glioma. Surgery, radiation, and chemotherapy are standard. New experimental treatments and clinical trials may also be options. Glioblastomas require intensive treatment, but research is ongoing to improve survival rates.

The Role of Molecular Markers in Treatment

In addition to grading, doctors now use molecular markers to better understand gliomas and refine treatment plans. These markers help predict tumor behavior and response to therapy.

Markers include:

1. Isocitrate Dehydrogenase (IDH) Mutation: This is associated with better outcomes; patients with grade 2 astrocytoma or grade 2 oligodendroglioma may be eligible for targeted drugs like vorasidenib, which can delay progression.
2. 1p/19q Co-Deletion: This is found in oligodendrogliomas and linked to improved prognosis; it responds well to temozolomide which is often used and while it may respond to PCV chemotherapy (procarbazine, lomustine, and vincristine) that is still being investigated.
3. ATRX Mutation: This helps differentiate astrocytomas from other gliomas.
4. TP53 Mutation: This is more common in astrocytomas and informs tumor classification.
5. TERT Promoter Mutation: This is frequently found in glioblastomas
6. MGMT Promoter Methylation: This predicts response to temozolomide chemotherapy; methylated tumors respond better.
7. EGFR Amplification: This is often seen in glioblastomas and signals a more aggressive tumor.
8. BRAF Alterations: This is common in pediatric and some low-grade gliomas; it may be treated with dabrafenib and trametinib.
9. CDKN2A/B Homozygous Deletion: This is found in more aggressive gliomas, indicating a poorer prognosis.

Understanding both the grade and molecular characteristics of a glioma allows for a more tailored approach to treatment, potentially offering better outcomes.

What’s Next After a Glioma Diagnosis?

A glioma diagnosis can feel overwhelming, but there are steps you can take to ensure the best possible care:

1. Ask Questions: Learn about your tumor’s grade, molecular markers, and available treatments.
2. Seek Multiple Opinions: Consulting a specialized neuro-oncologist or a major cancer center can provide additional insights.
3. Understand Treatment Options: Surgery, radiation, chemotherapy, and targeted therapies are all considerations.
4. Regular Monitoring: Follow-up MRIs and appointments are essential to track progression.
5. Build a Support System: Family, friends, and patient support groups can provide emotional and practical help.
6. Stay Informed on New Treatments: Ongoing research and clinical trials may offer additional treatment possibilities.

Questions to Ask Your Doctor

If you or a loved one has been diagnosed with a glioma, consider starting the conversation with your doctor with these key questions.

• What is the grade of my glioma?
• Have I been tested for molecular markers, and what do they mean for my treatment?
• What treatment options are available for my specific diagnosis?
• What are the possible side effects of treatment?
• How will we monitor the tumor after treatment?
• Are there clinical trials that might be beneficial for me?
• What lifestyle changes or supportive care options can help improve my quality of life?

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