Understanding Your Glioma Diagnosis & Grade
- Gliomas are graded on their aggressiveness, not staged like many other cancers. They are graded on a scale of 1 through 4 with 4 being the most aggressive.
- Low-grade gliomas are easier to treat, and some are cured with surgery alone.
- High-grade gliomas may require additional treatment after surgery with chemotherapy, targeted therapy, and/or radiation.
- Molecular subtypes are becoming increasingly important in diagnosis and treatment — so patients should speak to their doctors about testing.
However, it can be confusing for patients who may be accustomed to hearing about the “stage” of various cancers.
Read MoreHow Do Doctors Grade Gliomas?
When pathologists examine a glioma, they’re looking for specific features of the cancer under the microscope to determine its grade.These include:
- Cell Appearance: How abnormal do the tumor cells look? More abnormal-looking cells often mean a higher grade.
- Cell Division: How many cells are actively dividing? A high number of dividing cells indicates faster tumor growth.
- Vessel Formation: Are new blood vessels forming to feed the tumor? This is often seen in more aggressive gliomas.
- Necrosis: Is there evidence of dead tumor cells? This is a hallmark of the most aggressive types.
Based on these features, gliomas are graded on a scale from 1 to 4.
“Grade 1 is the least aggressive; grade 4 is the most aggressive,” Dr. Ghiaseddin explains. “In grade 1, this is what we primarily see in children — and if you can have a great surgical resection, where there’s no tumor that you can visually see, those patients are more than likely surgically cured. When we have grade 2 through grade 4 cancers in gliomas, that’s where things get a little bit trickier.”
What Does My Grade Mean?
Grade will help doctors determine the best way to treat a glioma. Here is an overview of what each grade means, and the likely treatment approach.
Grade 1 and 2 Gliomas (Low-Grade)
What They Are: These are slow-growing tumors. Grade 1 gliomas, such as pilocytic astrocytomas, are more common in children. Grade 2 gliomas can occur in both children and adults.
Prognosis: With Grade 1 tumors, a successful surgical resection can often be curative.
Treatment: Surgery is typically the first step, and additional treatments may not be needed unless the tumor recurs.
Grade 3 Gliomas (High-Grade)
What They Are: These tumors grow more quickly and are considered malignant.
Prognosis: Dr. Ghiaseddin explains that the treatment process is a bit more complicated in later stages. “We think of it as almost grains of sand, roots, or tentacles that we can’t necessarily see on an MRI.”
Treatment: Treatment will include more aggressive approaches. Surgery, radiation, and chemotherapy are often necessary.
Grade 4 Gliomas (The Most Aggressive)
What They Are: Grade 4 gliomas, such as glioblastomas, are the fastest-growing and most aggressive. They tend to invade surrounding brain tissue.
Prognosis: These tumors are locally aggressive and require intensive treatment.
Treatment: In addition to surgery, radiation and chemotherapy are almost always part of the treatment plan. New experimental therapies may also be considered.
The Role of Molecular Markers
In recent years, doctors have been using more than just the grading system to understand gliomas. Molecular markers—specific changes in the DNA or proteins of the tumor cells—can provide deeper insights into the behavior of the tumor and guide treatment decisions.
Here are some of the key markers for gliomas and what they mean:
- Isocitrate Dehydrogenase (IDH) Mutation — Tumors with IDH mutations generally have a better prognosis. This mutation may also make patients eligible for targeted drugs, such as Vorasidenib, which can prolong progression-free survival.
- 1p/19q Co-Deletion — This co-deletion is often seen in oligodendrogliomas and is linked to better outcomes. Patients with this mutation tend to respond well to a specific chemotherapy regimen called PCV (procarbazine, lomustine, and vincristine).
- ATRX Mutation — Found in tumors with IDH mutations, ATRX mutations can help distinguish between astrocytomas and oligodendrogliomas.
- TP53 Mutation — This mutation is more common in astrocytomas and can help differentiate them from oligodendrogliomas.
- TERT Promoter Mutation — Commonly found in oligodendrogliomas. In combination with 1p19q and IDH mutation, it can be a good prognostic marker to have, often called the triple positive. When found in glioblastomas, this mutation is associated with a poorer prognosis.
- MGMT Promoter Methylation — This marker predicts how well a glioblastoma will respond to the chemotherapy drug temozolomide. Methylated MGMT is linked to better outcomes. The marker also portends a good response to radiation, not just temozolomide.
- EGFR Amplification — This marker is associated with more aggressive tumors and is commonly seen in glioblastomas.
- BRAF Alterations — Common in pediatric gliomas and some low-grade gliomas, BRAF mutations can make patients eligible for targeted therapies like dabrafenib and trametinib.
- CDKN2A/B Homozygous Deletion — This deletion is frequently linked to aggressive tumors, including glioblastomas and IDH-mutant astrocytomas.
Understanding the grade of your glioma and its molecular markers allows your care team to create a personalized treatment plan. For example, knowing that your tumor has an IDH mutation or MGMT promoter methylation might open up additional treatment options or clinical trials.
What’s Next After Diagnosis?
Receiving a glioma diagnosis can be really overwhelming. SurvivorNet’s experts recommend taking a multi-pronged approach to ensure you are getting the best care possible.
This includes:
- Getting comfortable asking questions, like what the grade of your tumor is, whether you’ll be tested for molecular markers, what treatment options are available, and more
- Exploring multiple treatments options and asking your doctor for clarification during any point during the treatment process
- Getting on a schedule for regular follow-ups with your doctor
- Leaning on support systems, like family, friends, and support groups
- Staying positive and taking care of your mental health, too
While a glioma diagnosis can feel overwhelming, it’s important to remember that advances in research and treatment are happening every day. Understanding your tumor’s grade and molecular markers gives you and your medical team powerful tools to fight this disease. You’re not alone, and there is a community of healthcare providers, researchers, and fellow patients working toward better outcomes and, ultimately, a cure.
Questions to Ask Your Doctor
If you have been diagnosed with glioma and are unsure how to begin the treatment conversation with your doctor, consider starting with the following questions.
- What is the grade of my glioma?
- Can I be tested for molecular markers?
- What are the treatment options for people in my situation?
- How will I be monitored during and after treatment?
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