Getting Diagnosed
Physical Examinations
If a doctor suspects someone has a brain tumour, they’ll usually begin by examining brain function. This is often a neurological examination to inspect speech, hearing, vision and movement function. It may include checking reflexes, balance and coordination, testing muscle strength, the ability to feel sensation, and simple brain exercises such as memory tests.
A doctor may also use an ophthalmoscope, an instrument that allows them to examine the back of the eye, including the optic disc where the optic nerve enters the eye. They look for changes in the retina and optic disc, as well as eye and pupil responses. Swelling of the optic disc, called papilledema, can be a sign of raised pressure inside the skull. This pressure can be caused by a tumour, but it can also result from other conditions. Because the optic nerve carries visual signals from the eye to the brain, changes here can provide important clues about brain health.
Genetic testing
Cancer develops when genetic changes in a cell’s DNA disrupt normal growth and division. Over time, these changes can accumulate through random errors when cells divide or from exposures such as cigarette smoke or ultraviolet light. Most cancers arise from these acquired (somatic) changes, but about 5–10% are due to inherited mutations passed through families.
Doctors now use genetic tests to help classify and diagnose brain tumours. Since 2016, the World Health Organization (WHO) has incorporated molecular features, such as IDH mutation and 1p/19q co-deletion, into brain tumour classification. The most recent 2021 WHO update expanded this approach, meaning diagnosis is now based on both tumour appearance and key genetic markers. Doctors use genetic tests to examine gene changes in brain tumours to develop a more precise diagnosis and treatment plan.
In brain cancer, the most common gene changes that doctors test for include:
- 1p/19q co-deletion in oligodendroglioma. This gene change is linked to a higher likelihood of response to chemotherapy treatment.
- Gene changes in the IDH gene for gliomas. IDH gene changes are found in 70-80% of low-grade gliomas in adults. This gene change is linked with a better prognosis.
- MGMT methylation in glioblastoma.
This gene change is linked with better response to the chemotherapy drug, temozolomide.
Some gene changes that increase the risk of developing cancer can be inherited, meaning that it can be passed on in families. Being born with one inherited gene change doesn’t mean a person will definitely get cancer, but they have a higher risk compared to the general population.
For cancer to develop, further gene changes need to happen, often over many years.
People who have a genetic condition, such as neurofibromatosis, Li-Fraumeni Syndrome, tuberous sclerosis, Von Hippel Lindau disease or Turcot Syndrome, have an increased risk of developing a brain tumour.
If you’re concerned about your family history of brain cancer, speak to your general practitioner (GP). A GP can refer patients to genetic counselling services, which can provide people with information about their chance of developing cancer-based on their family history.
Procedures
Surgical Biopsy
A surgical biopsy is a procedure where a sample of tumour is removed by a neurosurgeon and sent to a pathologist for examination. The pathologist examines the tumour sample under a microscope and uses dyes to determine if the tumour is benign or malignant. These tests can also reveal the tumour type, which is important for guiding treatment options and prognosis.
The procedure does carry some risks, such as bleeding, stroke, and seizures. A biopsy may be done as a procedure on its own, or it might be part of a larger surgery to treat the tumour.
Types of Biopsy
Stereotactic biopsy
A stereotactic biopsy involves having an MRI or CT scan while wearing a special frame around the recipient’s head. Markers on the frame guide the surgeon to move the needle closer to the tumour.
The biopsy itself is performed by drilling a small hole in the skull. The surgeon then guides a small needle into the tumour to take a sample.
Neuronavigation biopsy
This uses advanced MRI or CT imaging with computer-assisted navigation instead of a fixed frame. The surgeon guides a needle into the tumour through a small opening in the skull to obtain tissue.
Open biopsy via craniotomy
Excisional biopsy
Lumbar Puncture
A lumbar puncture, also called a ‘spinal tap’, uses a needle to collect a sample of cerebrospinal fluid from the lower back. Cerebrospinal fluid is the fluid that surrounds the brain and spinal cord, which is sent to a laboratory to check for cancer cells.
A lumbar puncture can be uncomfortable but is considered a safe procedure. A small amount of anaesthetic is applied locally to the lower back. Then, a needle is inserted to collect a sample of cerebrospinal fluid from the spinal column. The needle does not go near the spinal cord, but some people might get a headache or backache following the procedure, which usually goes away by itself.
Medical Imaging Techniques
Magnetic Resonance Imaging (MRI)
A Magnetic Resonance Imaging (MRI) scan is an imaging test that produces very detailed images of the brain. Instead of using X-rays, MRI uses magnets, radio waves and a computer to produce images. MRI scans are considered safe, as they do not use gamma radiation.
The MRI scanner is a long tube surrounded by a magnet. The scanner sends and receives signals from cells in the body, which a computer then interprets to produce images of the brain. Sometimes a patient will be given an injection of a contrast medium or dye called gadolinium contrast medium, that makes some scans easier to read.
In rare cases, people may experience an allergic reaction to this dye. If you’ve had an allergic reaction to a CT contrast agent, it doesn’t mean you’ll react to the MRI contrast agent. There are several types of MRI scans to assess different structures of the brain.
Functional MRI (fMRI)
fMRI measures the small changes in blood flow that occur with brain activity. This type of MRI may detect abnormalities within the brain that cannot be found with other imaging techniques. For example, it can determine the function of parts of the brain in real-time, highlighting a tumour that has invaded sensitive regions of the brain.
Magnetic resonance spectroscopy (MRS)
Diffusion MRI
Magnetic resonance angiography (MRA)
Computer tomography (CT)
A computer tomography (CT) scan is an imaging test that uses X-rays to produce detailed images of what’s inside the body. The CT scan was previously known as a computerised axial tomogram, or CAT scan. As CT scans use X-rays, there’s a small amount of radiation risk associated with the procedure.
A CT scanner is a doughnut-shaped machine. The CT scanner moves in a circular motion around a person and takes X-rays of very thin slices of the body. These X-ray images are collected and processed in a special computer, that allow the doctor to look at the inside of the body just like looking inside a loaf of bread by slicing it.
Sometimes the person being scanned will be injected with a contrast medium or dye (called iodinated contrast medium) that makes some scans easier to read. In rare cases, people may experience an allergic reaction to this dye. If you’ve had an allergic reaction to an MRI contrast agent, it doesn’t mean you’ll react to the CT contrast agent.
A CT scan is used to identify bleeding and swelling in the brain, possibly as a result of a tumour. It’s also used for directing surgical and radiation treatments for brain cancers.
Positron emission tomography (PET)
A PET scan shows how active different tissues are in the body. It is particularly useful in cancer for detecting whether a tumour has spread, checking how well treatment is working, and finding recurrence.
For the test, a small amount of radioactive tracer is injected into a vein. The tracer collects in areas that use more energy, such as fast-growing cancer cells. The PET scanner then detects signals from the tracer to create images.
PET scans are usually combined with a CT scan (PET-CT), which provides both detailed images of body structures and information about cell activity.
In brain tumours, standard PET scans using glucose tracers can sometimes be difficult to interpret because normal brain cells also take up glucose. In some centres, specialised tracers such as amino acid PET are used to give more accurate results.
Whether you’re facing a new diagnosis or supporting a loved one, help is available. Click here to explore a range of support resources, services, and guidance to assist you through every step of the brain cancer journey.