What are the Different Brain Tumor Grades?

By The Preston Robert Tisch Brain Tumor Center

October 30, 2025

What are the Different Brain Tumor Grades?

When someone is diagnosed with a brain tumor, one of the first questions their medical team will address is: What grade is the tumor? Tumor grading is an essential step in determining how aggressive the tumor is, how it might behave, and which treatments are most effective.

At the Preston Robert Tisch Brain Tumor Center at Duke, we understand that receiving a brain tumor diagnosis can feel overwhelming. Knowing what the tumor grade means can help patients and families make more informed decisions and feel empowered throughout treatment.

What Is a Brain Tumor?

A brain tumor is a collection or growth of abnormal cells in the brain or spinal cord. These tumors can be primary, meaning they start in the brain, or metastatic, meaning they spread from another part of the body to the brain.

Each tumor behaves differently based on its type and grade. That’s why accurate diagnosis and grading are key to creating an individualized treatment plan.

How Are Brain Tumors Graded?

The brain tumor grading system classifies tumors based on how abnormal the tumor cells look under a microscope and how quickly they are likely to grow. Pathologists assign grades from 1 to 4, with higher numbers indicating more aggressive and faster-growing tumors.

Tumor grade is determined by several key features, including:

How abnormal the cells appear compared to healthy brain cells
How quickly the tumor cells are dividing
Whether the tumor is invading nearby tissue
Whether there are signs of dead cells (necrosis) or new blood vessel formation

This grading helps guide treatment decisions and gives doctors important insight into the tumor’s likely behavior.

The Four Brain Tumor Grades Explained

Grade 1 (Low-Grade, Least Aggressive)

Grade 1 brain tumors tend to grow slowly and are considered the least aggressive. They are often localized, meaning they do not spread to surrounding tissue. Because of this, they can sometimes be treated successfully with surgery alone if the entire tumor can be removed.

Common examples include pilocytic astrocytoma and certain meningiomas. After surgery, many patients can go long periods without recurrence, although regular monitoring is still recommended.

Grade 2 (Low-Grade but Infiltrative)

Grade 2 tumors also grow relatively slowly, but they have a higher tendency to invade surrounding brain tissue compared to grade 1 tumors. This means they may recur or progress to a higher grade over time.

Treatment for grade 2 tumors often includes surgery, and in some cases, radiation therapy or chemotherapy if the tumor cannot be completely removed or if there is evidence of progression.

Grade 3 (High-Grade, More Aggressive)

Grade 3 brain tumors grow faster and are more likely to invade nearby healthy brain tissue. These tumors often require a combination of surgery, radiation therapy, and chemotherapy.

Common symptoms may include worsening headaches, seizures, or neurological changes such as weakness or difficulty speaking. Because grade 3 tumors tend to recur, close follow-up care and imaging are critical to detect changes early.

Grade 4 (Most Aggressive)

Grade 4 tumors, such as glioblastoma, are the most aggressive type of brain tumor. They grow rapidly, form new blood vessels to sustain their growth, and often contain areas of dead tissue.

Treatment is typically aggressive and may include surgery, followed by radiation and chemotherapy.

Researchers at Duke’s Tisch Brain Tumor Center are continually studying new approaches to brain tumors in both adults and children. Pediatric clinical trials include targeted therapies and immunotherapies designed to attack tumor cells more precisely.

Can a Brain Tumor’s Grade Change Over Time?

In some cases, a tumor that was originally classified as a low-grade (grade 1 or 2) can transform into a higher grade over time. This process is known as malignant transformation or progression.

Because of this, patients who have undergone treatment for a low-grade tumor still require ongoing monitoring with regular imaging. Detecting any change early allows doctors to adjust the treatment plan and improve outcomes.

Why Tumor Grade Is Important for Treatment and Prognosis

Understanding the tumor grade is crucial for several reasons:

Guiding Treatment Decisions: Lower-grade tumors may be managed with surgery alone, while higher-grade tumors require more intensive treatment.
Predicting Behavior: The grade helps predict how quickly the tumor may grow or recur.
Determining Eligibility for Clinical Trials: Many research studies focus on specific tumor grades, giving patients access to innovative treatments.
Providing Prognostic Insight:> Tumor grade helps physicians discuss expected outcomes and survival rates more accurately.

Symptoms Across Brain Tumor Grades

Symptoms vary depending on tumor grade and location, but some common signs include:

Headaches, especially those that are new or worsening
Seizures
Changes in memory, speech, or cognition
Weakness or numbness on one side of the body
Vision or balance problems

Higher-grade tumors often produce more severe symptoms that progress more rapidly. Any new or unexplained neurological symptoms should be evaluated promptly by a healthcare professional.

Monitoring and Ongoing Care

Regardless of tumor grade, patients benefit from regular follow-up care and imaging to monitor for recurrence or progression. MRI scans are commonly used to assess whether treatment is working and to detect changes in the tumor’s behavior.

Duke’s comprehensive care approach includes not only medical treatment but also supportive services such as neuro-rehabilitation, nutrition guidance, and psychosocial support to help patients maintain quality of life during and after treatment.

Advancements in Brain Tumor Research

Ongoing brain tumor research continues to improve how tumors are classified and treated. Scientists and specialists at the Tisch Brain Tumor Center are studying genetic and molecular characteristics that may provide more accurate predictions of how tumors behave and respond to treatment.

This precision medicine approach is helping doctors move beyond traditional grading systems to develop personalized therapies. Through clinical research, patients at Duke have access to groundbreaking studies and innovative treatment options that may not be available elsewhere.

The Duke Approach to Brain Tumor Care

At the Preston Robert Tisch Brain Tumor Center, patients are cared for by a team of experts in neuro-oncology, neurosurgery, radiation oncology, and supportive services. This collaborative approach ensures that every patient receives individualized, evidence-based care.

From initial diagnosis to treatment and long-term follow-up, our goal is to combine compassionate care with leading-edge science to give each patient the best possible outcome.

Understanding the different brain tumor grades is a crucial part of navigating a brain tumor diagnosis. Whether you or a loved one is facing a new diagnosis or exploring treatment options, knowing what tumor grade means can help guide your decisions and improve communication with your care team.

At Duke’s Preston Robert Tisch Brain Tumor Center, our specialists are dedicated to advancing research, improving treatments, and supporting patients and families every step of the way.

Interested in discussing your diagnosis and exploring personalized treatment options? Visit our website to request an appointment. We also provide access to innovative clinical trials and the latest education & training to ensure you and your loved ones receive the most advanced care possible for brain tumors. You can also support the clinic by donating funds directly to patient care, research, education, and treatment for brain tumors.

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