What Causes Brain Tumours?

Benign Brain Tumours

These are non-cancerous growths which grow slowly and do not invade other tissues or organs. Most can be removed, depending on their location within the brain, and they do not grow back after removal. Benign brain tumours are rarely life-threatening, although unlike benign tumours in other parts of the body they can pose a risk to life. This happens if they compress on other parts of the brain.

Malignant Brain Tumours

These are cancerous cells that are potentially more life-threatening. They grow rapidly and can invade other tissues.

Brain tumour symptoms depend on the size of the tumour and its location within the brain. The most common brain tumour symptoms are severe headaches and fits, thought it must be remembered that brain tumours are rare causes of these symptoms. There are so many other reasons why an individual may be experiencing headaches and fits. Other brain tumour symptoms include;-

• Vision problems
• Difficulty balancing
• Dizziness
• Speech difficulties
• Personality/mood changes
• Confusion
• Loss of sensation in limbs

Brain tumours are rare, but known risk factors include;-

Age - tumours can strike at any age, but cancer is more common as individuals get older.

Other cancers - secondary tumours can form from the spread of cancer from other parts of the body such as lung cancer, breast cancer, and colon cancer.

Radiation - ionizing radiation is a risk factor. People who have had previous radiotherapy to the head are at a slightly increased risk. At the moment there is no conclusive proof that radiation from TVs, cell phones, or microwave ovens cause brain tumours.

Genetics - according to the cancer charity Cancer Research UK about 5% of brain tumours occur in people with a family history of brain tumours. The risk is raised if the following syndromes run in your family: neurofibromatosis type 1 and 2, tuberous sclerosis, Li-Fraumeni syndrome or Von Hippel-Lindau syndrome.

Increasingly researchers are uncovering genes linked to brain cancers which may provide new targets for treatment further down the line.

In July 2009 two promising studies appeared in The Journal of the American Medical Association. The first study linked mutations in 31 genes with brain tumours called gliomas. They allow the tumours to grow, and people with widespread mutations in these genes had worse survival rates than people who had these mutations to a lesser extent. The second study found that people with only one copy of the ANXA7 gene, which is a tumour suppressor gene, experienced worse survival rates than those with two copies of ANXA7.

Also in July 2009 scientists led by the University of Texas M.D. Anderson Cancer Center and the Institute of Cancer Research in the United Kingdom discovered that common genetic variations known as single nucleotide polymorphisms (places in the genome that vary from person to person) spread across five genes increase the risk of getting a brain tumour. Fourteen single nucleotide polymorphisms were discovered and the risk increased with the number of genes involved.

In September 2007 scientists at St.Jude Children's Hospital in Memphis published a paper about their discovery that brain tumour cells arise from stem cells that are located within small protective areas of the brain formed by blood vessels. The researchers found that these cancer stem cells were situated near blood capillaries which appeared to be feeding them. So in lab experiments they used drugs to block blood vessel formation which starved the stem cells of fuel and destroyed them. This provides a new way of killing brain tumours. Destroy the cancer stem cells and you wipe out the tumour.

The University of Texas M.D. Anderson Cancer Center

St. Jude Children's Research Hospital