Brain Tumor Diagnosis

If you have a brain tumor, it is important to get the most accurate diagnosis possible. This will help your doctor pinpoint the tumor to give you the most advanced treatment with the least impact on your body.

At MD Anderson, we have the most modern and accurate equipment available to home in on brain tumors and find out exactly how far they may have spread.

Our specialized staff truly sets us apart. The Brain and Spine Center has four renowned neuropathologists who focus only on diagnosing brain and spine tumors. They are an essential part of our team, and their expertise and experience can make a big difference in brain tumor treatment success.

Brain Tumor Diagnostic Tests

If you have symptoms that may signal a brain tumor, your doctor will examine you and ask you questions about your health, your lifestyle and your family history.

One or more of the following tests may be used to find out if you have a brain tumor and if it has spread. These tests also may be used to find out if treatment is working.

Imaging tests, which may include:

• CT (computed tomography) scans
• MRI (magnetic resonance imaging)

Biopsy: While imaging tests may show an area where there may be a brain tumor, doctors need a tissue sample to definitively diagnose a primary brain tumor. Tissue samples are retrieved through a biopsy. Doctors can perform a biopsy by removing a small sample of tissue with a needle or removing all or part of a tumor through surgery. Your neurosurgeon will determine which type of biopsy is best for your tumor.

Lumbar puncture: A small amount of cerebrospinal fluid (clear liquid in and around the brain and spine) is removed with a needle and examined under a microscope. This test may be done if doctors suspect a tumor has spread to the layers of tissue that cover the brain (the meninges) and into the spinal fluid.

Molecular testing: Some primary brain tumors, including some of the most common types of gliomas, are defined by their key molecular features resulting from tumor cell mutations. These features can be used to diagnose a tumor, provide a more accurate prognosis, and enhance the treatment plan. Key mutations include:

• IDH mutation: Grade II and III gliomas are tested for this mutation. In general, IDH-mutated tumors have a better prognosis than tumors without the IDH mutation. Gliomas without the IDH mutation are also known as IDH wildtype.
• 1p/19q co-deletion: This molecular feature is required for an oligodendroglioma diagnosis. It refers to the loss of parts of chromosomes 1 and 19. Unlike the IDH mutation, which only affects one gene, the 1p/19q co-deletion involves a large segment of DNA. This mutation generally indicates that a tumor will be more responsive to chemotherapy.
• MGMT promoter methylation: Testing for the MGMT mutation is required for many brain tumor clinical trials. MGMT is an enzyme that can make cancer cells more resistant to therapy. MGMT tumor methylation generally indicates better prognosis and may indicate better response to chemotherapy.

Brain Tumor Grading

Many cancers are organized by stages, which describe how much a cancer has spread. Primary brain tumors typically do not spread to other parts of the body, so they are not staged.

Instead, most brain tumors are graded on a scale developed by the World Health Organization. Tumor grading classifies tumor cells by how abnormal they look under the microscope and how quickly the tumor is dividing. Grade I tumors are the least aggressive, while grade IV tumors are the most aggressive.

Brain tumors can start out at a low grade and over time become more aggressive and transform into high grade tumors. They can also start as a high-grade brain tumor without ever being a low-grade tumor. 

Brain tumor grades include: 

• Grade 1 (low-grade): Grade 1 tumor cells are nearly identical to healthy cells. These tumors are slow growing and are usually associated with long-term survival.
• Grade 2: These tumor cells look slightly different than healthy cells. While they are still considered low-grade, grade 2 tumors are more aggressive than grade 1 tumors.  A grade 2 tumor has the potential to transform to a higher grade tumor.
• Grade 3: Grade 3 tumor cells look abnormal and actively reproduce. Grade 3 tumors grow faster than grade 2 tumors and have the potential to transform to a grade 4 tumors.
• Grade 4 (high-grade): Grade 4 tumors are the most aggressive. Tumor cells do not look like normal cells and are actively reproducing and growing. There may be areas of dead cells in the tumor.

Learn more about brain tumor treatment.