What Is A Low Grade Glioma? Types And Treatment

A low grade glioma is a slow-growing tumor that starts in the brain’s glial cells — the support cells that surround and protect neurons. The word “glioma” describes where the tumor begins, and “low grade” describes how the cells look under a microscope: they resemble normal cells and are not dividing rapidly. These tumors are classified as grade 1 or grade 2 by the World Health Organization (WHO), which sets them apart from the faster-growing high grade gliomas.

Low grade gliomas are uncommon. They tend to appear in younger adults compared with many other brain tumors, and some types are found mostly in children. Treatment has changed meaningfully in recent years as researchers have learned that the genetic makeup of a tumor matters as much as its grade.

What Is A Low Grade Glioma Types And Treatment?

A low grade glioma is a brain tumor that arises from glial cells and is assigned a grade of 1 or 2 under the WHO classification system. The grade reflects how abnormal the cells look and how quickly they appear to be growing, not where the tumor sits or how easily it can be treated.

The WHO updated its brain tumor classification in 2021. That update moved beyond looking only at cells under a microscope. It now builds genetic and molecular features into the diagnosis itself. This matters because two tumors that look identical under a microscope can behave very differently depending on their genetics.

Grade 1 tumors are the most benign. They grow slowly and, in some cases, can be cured with surgery alone. Grade 2 tumors are still low grade but have a greater tendency to grow back and, over years, some can transform into higher-grade tumors. That risk is why long-term follow-up matters even after successful treatment.

What Are the Main Types of Low Grade Glioma?

The main types are defined by the cell of origin and, increasingly, by molecular markers. The three you are most likely to encounter are astrocytoma, oligodendroglioma, and ependymoma.

• Astrocytoma (grade 2): Arises from star-shaped glial cells called astrocytes. A key genetic marker is a mutation in a gene called IDH. Tumors with an IDH mutation generally behave differently from those without it.
• Oligodendroglioma (grade 2): Arises from cells that make myelin, the fatty coating around nerve fibers. These tumors are defined in part by two molecular features: an IDH mutation and a specific chromosomal change called 1p/19q codeletion. That combination is associated with a better response to certain treatments.
• Ependymoma: Arises from cells lining the fluid-filled spaces of the brain and spinal cord. It can occur in children and adults and is classified separately from astrocytoma and oligodendroglioma.

There are also rarer low grade variants, including pilocytic astrocytoma (a grade 1 tumor seen mostly in children) and ganglioglioma. Your care team will identify the exact type from tissue removed during surgery or biopsy, along with molecular testing.

What Symptoms Does a Low Grade Glioma Cause?

Symptoms depend on where the tumor is and how much pressure it creates inside the skull. Because these tumors grow slowly, the brain often adapts, and symptoms can be subtle at first.

Seizures are one of the most common ways a low grade glioma first shows up. A tumor irritating the brain’s cortex can trigger abnormal electrical activity. Some people have a single seizure with no other warning signs.

Other possible symptoms include:

• Headaches, sometimes worse in the morning or with changes in position
• Weakness or numbness on one side of the body
• Changes in speech, memory, or personality
• Vision problems
• Gradual decline in balance or coordination

None of these symptoms is specific to glioma. Many other conditions cause the same problems. That is why imaging and, ultimately, a tissue diagnosis are needed to know what is going on.

How Is a Low Grade Glioma Diagnosed?

Diagnosis combines brain imaging with a tissue sample. An MRI is the standard imaging test. It shows the tumor’s location, size, and features, and it helps distinguish a low grade from a higher-grade tumor — though imaging alone cannot confirm the grade.

The definitive diagnosis comes from tissue. In many cases, surgeons remove as much of the tumor as is safely possible, and the removed tissue is examined and tested for molecular markers. When surgery is not the first step, a biopsy may be done to obtain a sample.

Molecular testing now plays a central role. Checking for IDH mutations and 1p/19q codeletion helps confirm the tumor type and gives information about likely behavior. This is one of the more important shifts in neuro-oncology: the genetic profile of a low grade glioma can influence treatment decisions as much as its grade does.

How Is a Low Grade Glioma Treated?

Surgery is the first-line treatment for most low grade gliomas. The goal is maximal safe removal — taking out as much tumor as possible without harming critical brain functions. For some grade 1 tumors, complete removal can be curative.

For grade 2 tumors, surgery is usually followed by observation or additional treatment, depending on the tumor’s molecular features, how much was removed, the person’s age, and symptoms. Treatment is increasingly tailored to the individual rather than applied the same way to everyone.

Additional treatments may include:

• Radiation therapy: Used to target remaining tumor cells. Whether and when to use it after surgery is a decision that balances tumor control against possible long-term side effects.
• Chemotherapy: Certain drugs are used, particularly for tumors with features that make them more responsive, such as oligodendrogliomas with 1p/19q codeletion.
• Targeted therapy and clinical trials: Research into treatments matched to a tumor’s genetics is ongoing. Some options are available through clinical trials rather than as standard care.

An important point: not every low grade glioma needs immediate aggressive treatment after surgery. For some people with a fully resected, slow-growing tumor, careful monitoring with regular MRI scans is a reasonable approach. The decision is genuinely individual and should be made with a neuro-oncology team.

What Is the Outlook for Someone With a Low Grade Glioma?

The outlook varies widely and depends on the tumor type, its molecular features, how much can be removed, the person’s age, and how the tumor responds to treatment. Because of this variation, general survival figures are less useful than they once seemed — a single number does not describe any one person’s situation.

What can be said with confidence is that low grade gliomas generally grow slowly and many people live for years after diagnosis. Grade 1 tumors have a better outlook than grade 2 tumors. Among grade 2 tumors, those with favorable molecular features tend to do better than those without.

One thing patients should understand: low grade gliomas have a tendency to recur, and over time some transform into higher-grade tumors. This is why ongoing follow-up with imaging is part of long-term care, even after a good initial result. It is a real risk, not a certainty, and the timeline varies greatly from person to person.

Because so much depends on individual factors, the most useful prognosis information comes from your own care team, who can interpret your specific tumor type, genetics, and surgical outcome.

What Follow-Up Care Is Needed?

Regular MRI scans are the backbone of follow-up. They allow the care team to watch for tumor growth or change before symptoms appear. The schedule is set individually and adjusted over time.

Follow-up also involves managing symptoms and any effects of treatment. Seizures may need ongoing medication. Rehabilitation — physical, occupational, or speech therapy — can help with function after surgery or as the tumor changes. Emotional and cognitive support matter too, and many centers offer these as part of routine care.

Living with a low grade glioma is often a long-term relationship with the health care system rather than a single episode of treatment. Planning for regular monitoring and knowing what symptoms to report is part of managing the condition.