Posted On: February 24, 2020
A brain tumour is a lump or growth of abnormally behaving cells that develops in the brain. This happens when the DNA of a cell mutates, causing it to grow and reproduce at increased rates and live beyond the average life expectancy of a healthy cell.
Brain tumours can be benign (non-cancerous) or malignant (cancerous). Brain tumours are relatively rare and the likelihood that you will develop a malignant brain tumour in your lifetime is less than 1%.
A primary malignant brain tumour is a tumour which originated in the brain or spinal cord. This is an extremely rare form of cancer.
Secondary brain tumours (also known as metastatic tumours) are tumours which have spread to the brain from other parts of the body. These are roughly ten times more common than primary brain tumours.
The risk of developing metastatic brain tumours varies depending on the type, severity and stage of cancer you have. Between 20 and 40% of people with cancer will develop brain metastases.
Brain metastases are more common in individuals with certain types of cancer, including:
Tumours can spread either through direct extension (spreading to nearby cells), through the lymphatic system, or through the bloodstream.
What causes the change from a normal cell to a cancerous cell is not yet fully understood, although some risk factors have been identified. For example working in an oil refinery, in the rubber industry or coming into regular contact with jet fuel, benzene or embalming fluid has shown to increase the risk of brain cancer.
Despite various claims, there has been no dependable evidence that cellular phones cause brain cancer.
Brain tumours are graded on a scale of 1-4. Grade 1 and 2 tumours are considered low grade or “benign” and Grade 3 and 4 tumours are considered high grade or malignant.
Low grade tumours are slow growing and relatively well contained. They are unlikely to spread to other parts of the brain and, if completely removed, have a low probability of returning.
These tumours are sometimes referred to as “benign”, this is somewhat misleading. Although they are not cancerous, low grade tumours can still cause harm by putting pressure on important areas of the brain and occasionally blocking the flow of cerebrospinal fluid (CSF).
Grade 3 and 4 tumours are known as malignant or cancerous tumours. They are characterized by rapid and aggressive growth and their high likelihood of spreading to other parts of the brain (or the spinal cord, although this is more rare). Malignant tumours are more likely to return even after intensive treatment. They usually require treatments such as radiotherapy or chemotherapy alongside surgery.
Some tumours are known as “mixed grade” because they contain both cancerous and non cancerous cells. These are graded by the highest grade of cell they contain.
Symptoms caused by position of tumour
The symptoms of brain cancer can vary greatly depending on where in the brain the tumour is located as well as its size and rate of growth.
The frontal lobe can be considered the “control panel” of your personality. It plays a vital part in controlling human cognitive behaviours such as memory, judgement, and emotional expression. Tumours in this area can cause:
The temporal lobe is involved in memory storage and the formation of long-term memory. It also holds the primary auditory cortex. This plays a crucial role in speech and vision. Tumours in the temporal lobe can cause:
This part of the brain processes information from the five senses. It also helps with visual and spatial orientation. Tumours in the parietal lobe can cause:
The occipital lobe processes visual stimuli. It analyzes, interprets and draws conclusions about what you can see. Tumours in the occipital lobe can cause loss of vision on one side.
The cerebellum regulates motor movements such as balance, coordination, and speech based on information from the sensory systems. It also plays a key role in learning motor behaviours. Tumours in the cerebellum can cause:
The brain stem is responsible for a variety of functions including:
Tumours in the brain stem can cause:
Usually a brain tumour is not diagnosed until after symptoms have manifested. If your GP suspects you have a brain tumour he will refer you to a specialist such as a neurologist who will provide a diagnosis. After this you will need a scan or test to find out more about the nature of the tumour.
MRI stands for Magnetic Resonance Imaging. It is the preferred method for diagnosing brain tumours as it is safe, non-invasive and capable of producing highly detailed images of the body.
When you have an MRI scan you will be put on a motorized bed that moves into a large tube. The process can last between 15 and 90 minutes. The procedure can be uncomfortable for people who are claustrophobic. If this is the case, you can ask your doctor for a mild sedative to help you relax.
If you have any metal in your body (for example a pacemaker) you may not be able to have an MRI scan. It may still be possible to make the MRI safe for you but you should always tell your doctor about any implants you have before undertaking an MRI.
MRI scans work using powerful magnetic fields and radio waves. When you are in the MRI machine the protons in your body are made to align by the magnets in the scanner. This is because protons have their own magnetic field. Protons in certain areas of your body are then knocked out of alignment by radio waves. Once the radio waves are switched off, the protons return to their previous position and send out radio waves. These are picked up by receivers and used to form an image of the body part based on the positioning of the protons in your body.
MRI scans can also distinguish different types of tissue in the body by measuring the speed at which protons from different tissues realign and the unique signals they give off.
Before an MRI scan you may be given an injection of contrast dye. This makes particular tissues and blood vessels show up in greater detail.
More advanced types of MRI such as Diffusion Weighted or Perfusion MRI’s may be used to give a more accurate diagnosis and grading of the tumour.
CT scans use X-ray photos taken from different angles. These photos are then compiled in a computer to provide a comprehensive three-dimensional image of the brain. CT scans are not used as commonly as MRI scans but they can provide more detailed imaging of the bones in the skull. This can be useful for determining the effects of a tumour on the skull.
Brain tumour care is usually done by a multidisciplinary team consisting of different types of doctors and health care professionals. As well as treating the tumour itself your treatment plan will also focus on managing symptoms and side effects.
Treatment will vary depending on:
Surgery involves removing the tumour and some surrounding healthy tissue. For a low-grade tumour this may be the only treatment that is required.
Surgery may also be used to reduce the size of the tumour if it cannot be removed completely or to take tissue samples for laboratory analysis. Even if the tumour cannot be cured, surgery can relieve symptoms caused by the tumour putting pressure on the brain.
Some tumours cannot be treated with surgery because they are in a place the surgeon cannot reach or are near a vital part of the brain that could be damaged by an operation.
Radiation therapy involves using X-rays or other particles to destroy tumour cells. Radiation therapy can be used to stop or slow the tumour’s growth and is performed by a radiation oncologist, usually in conjunction with other treatments such as surgery and chemotherapy.
You will likely be given a course of treatment involving a set number of treatments over a period of time. The amount of radiation will vary depending on the grade and location of the tumour. Advances in the field mean that radiation can be aimed at the tumour with high levels of precision and minimizing the amount of radiation that healthy tissue is exposed to.
Some side effects of radiation therapy include:
These side effects usually disappear once the treatment has finished, however damage to healthy brain tissue can cause longer term side effects.
Chemotherapy uses drugs to destroy tumour cells, halt their growth or alleviate symptoms. It is usually given after surgery and may be given in conjunction or after radiotherapy.
Chemotherapy is usually given on a set schedule. It can consist of one drug or a combination of drugs given at once.
Drugs given for brain tumours include:
When undergoing chemotherapy you will be given an MRI scan every 2-3 months to monitor your progress.
Side effects of chemotherapy include:
Side effects will vary depending on the individual and the dose of medication and will usually go away once treatment is finished.
Rare side effects include hearing loss and kidney damage.
Targeted therapy works by specifically targeting the tumour’s specific genes and proteins as well as environments which help it grow and survive. Targeted therapy can halt a tumour’s growth while limiting damage to healthy tissue. As the treatment is based around the individual properties of the tumour, your doctor may perform tests to identify genes, proteins and other factors of the tumour.
There are two types of targeted therapy that can be used for brain tumours:
Alternating electric field therapy uses a portable device with electrodes on the outside of your head. These electrodes generate alternating electrical fields which are thought to affect the parts of a cell needed for tumour growth and spread.
Alternating electric field therapy is used to treat newly diagnosed or recurrent glioblastoma.
Palliative (or supportive) care focuses on managing symptoms and side effects of treatment as well as the social, emotional and financial effects of a brain tumour. Palliative care is intended to improve how you feel during treatment by managing non-medical needs as well as providing support patients and families and managing side effects.
Palliative care usually works best when it is begun immediately after you receive a diagnosis. Patients receiving palliative care generally experience a better quality of life, less severe symptoms and greater satisfaction with their treatment.
Palliative care can include various therapies, medications, changes in diet, emotional and spiritual support and relaxation techniques such as meditation, mindfulness, and yoga.
Before beginning supportive care it is important to discuss your specific goals with your doctor as well as keeping them updated throughout your care of any problems or side effects you are experiencing.