Diagnosis

Astrocytoma is diagnosed using several tests and procedures. They include a neurological exam, imaging scans and a biopsy. These help the healthcare team confirm the type, grade and genetic features of the tumor.

Neurological exam

During this exam, your healthcare team asks about your symptoms. You may have tests to check your vision, hearing, balance, coordination, strength and reflexes. Trouble in one or more of these areas may help show the part of your brain affected by a brain tumor.

Removing a sample of tissue for testing

A biopsy is a procedure to take a sample of tissue from the tumor for testing. After imaging shows a possible tumor, a biopsy is needed to confirm the diagnosis and learn more about the tumor's molecular features. The sample often is taken during surgery to remove the astrocytoma.

If the astrocytoma is in a spot that's hard to reach with surgical tools, a needle might be used to get the sample. The tissue goes to a lab for review under a microscope. Tests can determine the types of cells and how quickly they grow. This is called molecular testing. During this testing, doctors also study the tumor's genes and molecules. Types of molecular testing include:

  • IDH (isocitrate dehydrogenase) testing. This test looks for a change in the IDH1 or IDH2 gene. Tumors with this change usually grow more slowly and respond better to treatment.
  • MGMT (O-6-methylguanine-DNA methyltransferase) promoter methylation. This test looks at whether this DNA repair gene is "turned off." If it is, the tumor may respond better to chemotherapy with the medicine temozolomide.
  • 1p/19q codeletion. This tests whether parts of chromosomes 1 and 19 are missing. This helps confirm whether the tumor is an oligodendroglioma. This type of tumor often responds well to radiation and chemotherapy.

A biopsy is the only way to confirm the diagnosis of astrocytoma and find out what type and grade it is. Testing done on the biopsy sample can help predict how the tumor will grow and behave, and which treatments are most likely to be effective.

Together, these tests help the care team confirm the exact tumor type and predict how it will behave, and choose the most effective treatment plan.

Can spinal taps or blood tests detect astrocytoma?

No, spinal taps and blood tests usually can't detect an astrocytoma. Astrocytomas form inside the brain or spinal cord. Routine blood work or spinal fluid tests don't show clear signs of these tumors.

In some rare cases, a healthcare professional may do a spinal tap (lumbar puncture) to check for tumor cells in the cerebrospinal fluid (CSF). This may be done if there's concern the tumor has spread within the brain or spinal canal. But this test is used only in special situations after imaging suggests the tumor has spread.

Blood tests are mainly used to check general health and to see how the body is handling treatment, not to find the tumor itself.

Imaging tests

To see the tumor more clearly, your care team may use imaging tests. A brain MRI is often used to diagnose brain tumors. Sometimes special types of MRI, such as functional MRI, perfusion MRI, or MR spectroscopy, are used. Other imaging tests may include CT and positron emission tomography (PET) scans.

What scans are best for diagnosing astrocytomas?

MRI with contrast is the main scan for spotting and studying an astrocytoma because it shows brain and spinal cord tissue in much greater detail. CT is mainly used if MRI isn't possible or in emergencies. MRI with contrast helps doctors see both small, slow-growing and aggressive tumors clearly.

Does a pilocytic astrocytoma look different on an MRI?

On MRI, a pilocytic astrocytoma looks smoother and more organized. Higher grade tumors look rougher and more destructive in the surrounding tissue. A grade 1 pilocytic astrocytoma usually looks different from higher grade astrocytomas because it grows slowly. It also tends to stay well defined instead of blending into nearby brain tissue.

Pilocytic astrocytomas often look like cysts. They are round or oval masses with a fluid pocket. The tumor's solid part lights up clearly on the scan after the contrast is given. Pilocytic astrocytomas have clear borders and less swelling around them.

Higher grade astrocytomas, such as diffuse, anaplastic or glioblastoma types, often look more uneven and spread into nearby brain tissue. They usually have blurred edges, swelling around the tumor and patchy bright areas after contrast is given. These bright spots happen because parts of the tumor may have dead cells. Or they may have new and unusual looking blood vessels.

Special tests can provide detailed information about the tumor cells. Tests might look for changes in the genetic material of the tumor cells, called DNA. The information helps your healthcare team understand what to expect and decide on the best treatment for you.

Treatment

Astrocytoma treatment depends on the tumor's grade, size and location. Common treatments include surgery, radiation therapy and chemotherapy. In some cases, treatment may include targeted therapy or clinical trials.

  • Surgery to remove the astrocytoma. A brain surgeon called a neurosurgeon works to remove as much of the astrocytoma as possible. The goal is to remove the whole tumor. If the tumor is in a spot that is hard to reach, it may be too risky to remove it all. Even so, taking out part of the astrocytoma can help ease your symptoms.

    For some people, surgery may be the only treatment needed. For others, more treatments may be recommended to kill any remaining tumor cells and lower the risk of the tumor coming back.

  • Radiation therapy. Radiation therapy uses powerful energy beams to kill tumor cells. The energy can come from X-rays, protons and other sources. During radiation therapy, you lie on a table while a machine moves around you. The machine sends beams to exact points in your brain. The treatment only takes a few minutes.

    Radiation therapy may be recommended after surgery. It can be used if the cancer wasn't removed completely or if there's a high risk the cancer will return. Radiation also may be used with chemotherapy for cancers that grow quickly. For people who can't have surgery, radiation therapy and chemotherapy may be used as the main treatments.

  • Chemotherapy. Chemotherapy uses strong medicines to kill tumor cells. Chemotherapy medicines can be taken in pill form or given through a vein. Sometimes, a circular wafer of chemotherapy medicine can be put in your brain during surgery. There, it slowly dissolves and releases the medicine.

    Chemotherapy is often used after surgery to kill any tumor cells that might remain. It also can be used with radiation therapy for tumors that grow quickly.

  • Supportive care. Supportive care, sometimes called palliative care, helps manage pain and other symptoms of a serious illness. A team of specialists works with you, your family and your care team members to provide extra support. Supportive care can be given along with treatments such as surgery, chemotherapy or radiation. It often begins when treatment starts. You may not need to wait for complications to appear before receiving supportive care.

Surgery is usually the first step in treating astrocytoma. The goal is to remove as much tumor as is safely possible. What happens next depends on the tumor's grade, which is based on how the cells look and act under a microscope.

  • Grade 1. Surgery is often the only treatment needed. These tumors grow slowly and are usually well defined, so they can often be removed completely. If the entire tumor is taken out, people often do not need further treatment.
  • Grade 2. Treatment typically includes surgery, often followed by radiation therapy, chemotherapy or both. Even though these tumors grow slowly, they tend to spread into nearby brain tissue, which makes them harder to remove completely. Radiation therapy and chemotherapy help kill any remaining tumor cells and lowers the chance that the tumor will come back.
  • Grades 3 and 4. Treatment often combines surgery, radiation therapy and the chemotherapy medicine temozolomide. Because these tumors grow and spread faster, healthcare professionals use a more aggressive approach. In some cases, targeted therapies such as IDH inhibitors or clinical trials also may be considered.

Your care team will create a treatment plan that fits your needs.

Astrocytoma treatment: Watchful waiting

Watchful waiting for low-grade astrocytoma, also called active surveillance, can be safe for some small, slow-growing tumors when the risks of surgery outweigh the benefits. But close monitoring is essential, and treatment should begin at the first sign of change.

Watchful waiting can be considered in select cases of low-grade astrocytoma, but it depends on several key factors:

  • The tumor is small and does not cause symptoms. If the tumor was found by chance and does not affect brain function, your care team may monitor it closely with MRI scans instead of treating it right away.
  • Surgery would cause high risk. If the tumor is in a deep or critical area of the brain where surgery could harm important functions, watchful waiting can sometimes be safer until there is clear growth or change.
  • Diagnosis is uncertain. When the imaging suggests a low-grade tumor but a biopsy would be risky, watchful waiting can help track tumor growth over time.

Astrocytoma clinical trials and emerging treatments

Researchers are testing new astrocytoma treatments through clinical trials, including targeted therapy, immunotherapy and Tumor-Treating Fields (TTFields). Many of these treatments are still in clinical trials, where experts test new medicines and technologies to see how safe and effective they are. Clinical trials test new treatments such as vaccines, chimeric antigen receptor (CAR)-T cell therapy and viral therapies that target tumor cells directly.

A clinical trial may be an option for some people, especially if the tumor returns or stops responding to standard treatments. Some trials study targeted therapy, which uses medicines designed to act on certain proteins or genes in tumor cells. Other trials look at immunotherapy, which helps your body's defense system fight the tumor. Trials also are exploring better ways to combine surgery, radiation and chemotherapy.

Treatments being studied include:

  • Temozolomide. Temozolomide is a chemotherapy medicine already used with radiation therapy to treat higher grade astrocytomas. Researchers are studying ways to make it work even better, such as changing how it's given or combining it with new treatments to improve results and lower side effects.
  • IDH inhibitors. Some astrocytomas have changes in a gene called IDH. Medicines known as IDH inhibitors are being tested for people with this gene change. Studies suggest these treatments might help slow tumor growth, and more research is underway.
  • Tumor-treating fields, also called TTFields. TTFields use low-intensity electrical fields to disrupt how cancer cells grow and divide. This treatment is already approved for glioblastoma, which is a high-grade astrocytoma. Studies show that TTFields can help people live longer when used with standard treatments such as radiation therapy. Researchers continue to study how best to combine TTFields with other therapies.

Taking part in a trial may give you access to these options before they are widely available. Because these treatments are still being studied, the risks and benefits may not yet be fully known. Your healthcare team can help you decide if a clinical trial is right for you.

How treatment differs for spinal cord or brainstem astrocytomas

Treatment for spinal cord astrocytoma and brainstem astrocytoma differs because surgery in these areas can affect vital nerves and functions.

Location Typical first treatment Other treatments Why it's different
Spinal cord Surgery to remove as much tumor as is safely possible Radiation or chemotherapy if the tumor can't be fully removed or if it's high grade. The tumor grows inside the spinal cord. Surgeons must protect the nerve pathways that control feeling and movement.
Brainstem Often biopsy only or very limited surgery, if safe Radiation is the main treatment. Chemotherapy may be added, especially in children. The brainstem controls breathing, heart rate and swallowing, so surgery is often too risky.

Preparing for your appointment

See a healthcare professional if you have any symptoms that worry you. If your health professional thinks that you may have astrocytoma, you'll likely be referred to a specialist. This specialist might be a cancer doctor, called an oncologist. You also may see a surgeon who specializes in operating on the brain, called a neurosurgeon.

Because appointments may be quick, it helps to come prepared. Here's some information that may help you get ready.

What you can do

When you make the appointment, ask if there's anything you need to do ahead of time, such as not eating before a specific test. Make a list of:

  • Your symptoms, even ones that don't seem related.
  • Key personal information, including major stresses, recent life changes and family medical history.
  • All medicines, vitamins or supplements you take, including the doses.
  • Questions you'd like to ask.

Take a trusted family member or friend along, if possible, to help you remember the information you're given.

For astrocytoma, some basic questions to ask your healthcare professional include:

  • Do I have cancer?
  • If the tumor isn't cancerous, do I still need to have it removed?
  • Do I need more tests?
  • What are my treatment options?
  • What are the potential risks or side effects for these treatment options?
  • Will any of these treatments cure my cancer?
  • Can I have a copy of my pathology report?
  • How much time can I take to consider my treatment options?
  • Are there brochures or other printed materials that I can take with me? What websites do recommend?
  • What would happen if I decide not to have treatment?

Don't hesitate to ask any other questions you have.

What to expect from your doctor

Your healthcare professional is likely to ask you several questions, such as:

  • When did your symptoms begin?
  • Do your symptoms come and go, or are they constant?
  • How severe are your symptoms?
  • What, if anything, seems to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?
By Mayo Clinic Staff