Brain tumours

The exact causes of the development of brain tumours and brain cancers remain poorly defined. Although they do not appear to be hereditary in nature, they are more frequent in certain hereditary syndromes or certain diseases [4]. However, two risk factors have been associated with their development.

Irradiation of the head and neck (X-rays, radiation therapy) may slightly increase the risk of developing a brain tumour several years later.

Weakening of the body’s defences (immunosuppression) in certain hereditary diseases and chronic illnesses, such as AIDS, can increase the long-term risk of developing a brain lymphoma.

Other risk factors have sometimes been associated with the development of brain cancer, such as age, certain viruses, or exposure to pollutants (pesticides, lead, etc.).

Brain tumour symptoms mainly depend on tumour size, growth rate and location in the skull, based on the proximity to critical structures. Benign tumours generally cause symptoms that appear slowly, sometimes so discreetly that they are not felt until several months or years later. By contrast, malignant tumours develop quickly, often in a matter of days or weeks, and can cause more serious symptoms, sometimes with a sudden onset. [1]

The main symptoms of brain tumours include [5]:

• headache, sometimes more intense in the morning or during activities
• seizures
• nausea and vomiting
• changes in personality, thinking, mood and behaviour
• difficulty speaking or understanding words
• abnormal movements, difficulty walking, weakness on one side of the body
• fine motor skill disorders
• difficulty swallowing or eating
• visual disturbances such as slight blurriness, double vision or loss of vision
• hearing and balance problems
• numbness in one part of the body
• confusion
• coma

Case history, anamnesis, and physical examination

Diagnosis of a brain tumour begins with a detailed anamnesis, including a description of the symptoms experienced, in addition to a personal and family medical history. A physical examination is also essential and may include vision and hearing tests in order to rule out the many conditions causing similar symptoms.

Imaging

Magnetic resonance imaging (MRI) is the main diagnostic tool for brain tumours that affect soft tissue (i.e., not bone), with the exception of those involving the skull itself. Certain types of MRI, combined with angiography, spectroscopy or perfusion, can be used to visualize the blood vessels, tumour features less visible on MRI, or blood flow feeding the tumour.

Computed tomography (CT scan) is often the first imaging step in detecting a mass effect. CT imaging can also be used to assess the bone structures surrounding a tumour, since it can be used in patients for whom MRI is not an option, such as severely obese or claustrophobic individuals.

Positron emission tomography (PET) is also used to confirm whether certain regions targeted on MRI are likely to be cancerous, showing high levels of radiotracer activity, or are scar tissue with low radiotracer activity.

Biopsy

If the tumour is operable, a biopsy of the suspicious tissue is taken during surgery to remove the tumour and the tissue then sent for microscopic analysis.

If the tumour is inoperable due to its depth in the brain, a stereotactic biopsy may be considered. In this technique, a special frame is placed around the patient’s head to limit movement while the surgeon inserts a fine biopsy needle directly into the tumour while MRI is used to precisely guide the procedure.

Laboratory work

Blood and urine tests are generally of limited value in diagnosing brain cancers. However, in some pituitary tumours, measuring the levels of the hormones they secrete, such as growth hormone in acromegaly and prolactin in prolactinoma, can help diagnose the tumour and monitor its progression.

In other cases, these analyses are mainly used to assess the proper functioning of other organs and to ensure that the patient is fit to undergo the surgical and other procedures required for the treatment.

Whenever possible, brain tumour treatment usually begins with surgery, often followed by radiation therapy and/or chemotherapy. In some instances, radiosurgery (Gamma Knife), a technique that involves directing an X-ray precisely at the tumour to destroy it, can be used.

Corticosteroids can be used to reduce intracranial pressure and anticonvulsants to control epileptic seizures.

For secondary cancers resulting from metastases of cancers from another site, the treatment is generally similar to that for the primary cancer, using the same drugs.

Malignant brain tumours significantly limit a patient’s life expectancy. They pose a particular challenge because their progression can rapidly compromise a patient’s ability to make important decisions about end-of-life medical care, including palliative care and, in Quebec, at least, the personal choice to seek medical aid in dying (MAID).