Diagnosis of brain and spinal cord tumours

Diagnosis is the process of finding out the cause of a health problem. Diagnosing cancer often means first ruling out other health conditions that share similar symptoms with cancer. It can be a very worrying time for you and your loved ones. Sometimes this process is quick. Sometimes it can feel long and frustrating. But it’s important for doctors to get all the information they need before making a diagnosis of cancer.

Diagnosing a brain or spinal cord tumour usually begins with a visit to your family doctor. Your doctor will ask you about any symptoms you have and may do a physical exam. Based on this information, your doctor may refer you to a specialist or order tests to check for brain or spinal cord cancer or other health problems.

The following tests are commonly used to rule out or diagnose a brain or spinal cord tumour. Your doctor may also order other tests to check your general health and to help plan your treatment.

Your health history is a record of your symptoms, risks and all the medical events and problems you have had in the past. Your doctor will ask questions about your history of:

• symptoms that suggest a brain or spinal cord tumour
• radiation exposure
• inherited conditions
• conditions or medications that weaken the immune system
• any other cancer diagnosis

Your doctor may also ask about a family history of:

• brain or spinal cord tumours
• other cancers

A physical exam allows your doctor to look for any signs of a brain or spinal cord tumour. During a physical exam, your doctor may also do a neurological exam, a vision exam and a hearing exam.

A neurological exam includes checking your:

• reflexes, balance and coordination
• fine motor skills, such as picking up an object or writing something by hand
• muscle strength
• response to pain
• awareness of your surroundings
• judgment, reasoning and memory
• ability to use numbers
• ability to speak, read or write

A vision exam includes checking eye movement and field of vision.

A hearing exam tests how well you hear sounds.

Find out more about physical exams and hearing tests.

Magnetic resonance imaging (MRI) uses powerful magnetic forces and radiofrequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3D pictures.

An MRI is considered the best way to look for tumours in the brain and spinal cord. The following special types of MRIs might be done.

MRA (magnetic resonance angiography) shows the structure of blood vessels in the brain. It can help a surgeon plan an operation if it is needed for treatment.

MRS (magnetic resonance spectroscopy) looks at the chemical makeup of the tissues in the brain. It can show the difference between normal brain tissue and abnormal tissue that could be a tumour.

Perfusion MRI (magnetic resonance perfusion) shows the amount of blood going through different parts of the brain and can give an idea of how fast a tumour is growing. It can help determine the best place to take a biopsy and may be used after treatment to see if an abnormal area is a tumour or scar tissue.

Find out more about MRIs.

A computed tomography (CT) scan uses special x-ray equipment to make 3D and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.

CT scans are not used as often as MRIs to diagnose or stage a brain tumour, but they may be used to provide better detail of the bone structures near the tumour or when an MRI can’t be done.

A CT angiography (CTA) creates detailed images of blood vessels in the brain, which can be useful in planning surgery.

Find out more about CT scans.

A positron emission tomography (PET) scan uses radioactive materials called radiopharmaceuticals to look for changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3D colour images of the area being scanned.

A PET scan may be used to determine if abnormal areas seen on an MRI or a CT scan are likely to be cancerous. It can also be used after treatment to see if an abnormal area is a tumour or scar tissue.

Find out more about PET scans.

During a biopsy, the doctor removes tissues or cells from the body so they can be tested in a lab. A report from a pathologist will show whether or not cancer cells are found in the sample.

Biopsies for brain and spinal cord tumours are done by a neurosurgeon who specializes in treating these types of cancer.

The following biopsies are used for brain or spinal cord tumours.

If imaging tests show that the tumour can be treated with surgery, a biopsy sample will be taken during surgery to remove the tumour.

During the surgery (called a craniotomy), part of the skull is removed so the surgeon can reach the tumour. All or most of the tumour is removed. Small samples of the tumour are examined while the patient is still in the operating room. This diagnosis can help guide treatment, including whether further surgery should be done at that time. The bone that was removed from the skull to make an opening is usually replaced after the tumour is taken out.

A stereotactic (closed) biopsy may be used for tumours that likely can’t be removed with surgery, such as tumours that are deep within the brain.

The scalp is frozen with a local anesthetic or a general anesthesic may be used.

A special frame is fastened to the head to hold it in place so that the surgeon can accurately target the tumour. The surgeon makes a cut (incision) in the scalp and drills a small hole in the skull. An MRI or a CT scan is usually used to help the surgeon guide a hollow needle into the tumour and remove tissue samples for biopsy.

Find out more about biopsies.

A lumbar puncture is a procedure that removes a small amount of cerebrospinal fluid (CSF) to be examined under a microscope. During the procedure, the doctor inserts a needle into the spine of the lower back and removes CSF from the space where it circulates within the spinal cord. The pathologist looks for any cancer cells in the CSF.

Lumbar punctures are not usually done to diagnose brain and spinal cord tumours, but they may be done after a diagnosis of certain types of brain tumours that are known to spread to the CSF.

Find out more about lumbar punctures.

A spinal angiography uses x-ray and a radioisotope dye to take pictures of the blood vessels that supply a tumour in the spinal cord.

A catheter is put into the artery in the groin and threaded up to the area of the tumour. The dye is injected through the catheter into the blood vessels, and x-rays are taken as the dye flows through them. These images of the tumour and its blood vessels help the neurosurgeon decide how to remove the tumour safely.

Find out more about angiography.

Cells and tissues are analyzed in the lab to look for cancer. A report from a pathologist will show whether cancer cells are found in the sample and what type of brain or spinal cord tumour has been found.

There are different ways to study cells and tissues. Biomarker testing (also called molecular testing) and methylation profiling are used for brain or spinal cord tumours.

Find out more about cell and tissue studies.

Biomarker testing is the measurement of any cellular, molecular, chemical or physical change to study a normal or abnormal process in the body. It can be done to check the risk for, presence of or progress of a disease.

Some biomarker tests that are used in the diagnosis of brain and spinal cord tumours look for genes or proteins found in the tumour cells that can help identify the type of tumour. Other tests look for alterations to certain genes in the brain or spinal cord cells.

Biomarker testing can help your healthcare team plan your treatment, since some treatments are only effective if the tumour has a particular biomarker. The results are also used to predict how well a tumour might respond to certain treatments and help your healthcare team determine prognosis and survival.

The World Health Organization (WHO) uses biomarkers as part of the classification and grading of brain and spinal cord tumours.

Some of the biomarkers looked at for brain and spinal cord tumours are:

• IDH1 and IDH2
• MGMT
• NTKR
• 1p/19q co-deletions
• TERT promoter mutations
• BRAF
• AKT1
• PIK3CA
• EGFR
• NF1 and NF2
• BAP1
• MYC, MYCN
• YAP1
• ZFTA

Biomarker testing identifies and describes the changes to genes using these terms:

• Wild type means that there are no changes in the gene.
• Mutant means that changes have been found in the gene.
• Fusion means that 2 genes have joined (fused) together.
• Amplified means that there is an increased number of copies of the gene in a cell.
• Deleted or co-deleted means that part of the chromosome in the gene is missing (deleted) or is missing along with another part of the chromosome (co-deleted).

Methylation profiling looks for changes caused by methylation.

A methyl group is a group of tiny particles (atoms) connected to one another. A methyl group can be added to the proteins, DNA or other molecules in cells by a chemical reaction called methylation. When this happens, it can change how the molecules work or act in the body. The changes caused by methylation can increase the risk of cancer and other diseases.

Methylation profiling can help identify different types of brain or spinal cord tumours, especially if other tests haven’t confirmed the type.

Blood tests are not used to diagnose brain or spinal cord tumours. But they are routinely done to provide a baseline before any planned treatment. They can provide helpful information about your general health, how other organs are functioning, other medical conditions and the possible risks of treatment.

Blood tests that may be used are:

• a complete blood count (CBC), which measures the number and quality of white blood cells, red blood cells and platelets
• blood chemistry tests, which measure certain chemicals in the blood and show how well certain organs, such as the liver and kidneys, are working

Find out more about a complete blood count and blood chemistry tests.

Find out more about a diagnosis. To make the decisions that are right for you, ask your healthcare team questions about a diagnosis.