What Causes Brain Tumours?

Learning that you or a loved one has a brain tumour can be a confusing and frightening experience. You probably have a lot of questions about what caused it and what the future holds for you and your family. Understanding the risk factors associated with brain cancer can provide clarity and a sense of control. On this page, we’ll explore the various risk factors that can contribute to the development of brain tumours.

What is a Brain Tumour?

A brain tumour is an abnormal growth of cells in the brain that can be cancerous (malignant) or non-cancerous (benign).

The cells in our body naturally grow, multiply and renew. Sometimes, an error in the genetic-code means a cell with an abnormal ability to grow is made. Our bodies normally detect and destroy these abnormal cells, but sometime, they multiply, forming a tumour.

Malignant vs Benign brain tumours

Benign or noncancerous tumours are generally slow growing and are unlikely to spread to other parts of the brain. But, even if they are benign, they can press on important structures such as nerves, blood vessels and hormonal glands if they grow big enough and may need surgical removal. In some rare cases, non-cancerous tumours can change into cancerous ones.

Some examples of benign tumours are:

• Meningioma – most meningiomas are benign but some can be malignant

• Pituitary adenoma

• Craniopharyngioma

Malignant or cancerous tumours are faster growing and invasive, meaning they can spread into nearby blood vessels, lymph nodes and into other parts of the body. Brain cancer can be treated with surgery, but radiotherapy and chemotherapy may be required too. Even if they are treated, malignant brain tumours can return.

Some examples of malignant brain tumours are:

• Glioblastoma

• Primary CNS lymphoma

• Astrocytoma

Brain Cancer vs. Primary Brain Tumours

Primary Brain Tumours

These tumours start in the brain. They can be benign or malignant (brain cancer) and generally do not spread to other parts of the body. 

Secondary Brain Tumours (Metastatic Brain Tumours): 

These are cancerous tumours that develop elsewhere in the body (e.g. the lung) and then spread to the brain.

What causes brain tumours?

Understanding the risk factors for brain cancer can help provide insight into how it develops. Each year, thousands of people are diagnosed with a primary brain tumour, and an exact cause isn’t always known. Typically, a diagnosis of brain cancer isn’t related to anything you have or haven’t done and only a small percentage—about 3%—of cases are preventable. There are over 100 different types of brain tumour and no single risk factor accounting for the majority of cases has been found. Risk factors can be either preventable or non-preventable.

Non-preventable risk factors

Some risk factors for brain tumours are beyond our control. These include demographic and genetic influences, such as age, gender, and family history, as well as certain medical conditions and treatments. Understanding these factors can help in early detection and management.

• Age – The risk of cancer is higher in older adults and this includes brain cancer, which is more common in those over 75 years old.

• Gender – Women in the UK are slightly more likely to be diagnosed with a brain tumour over their lifetime than men.

• Genetics – Certain genetic conditions can increase the risk of developing a brain tumour, these include – Neurofibromatosis (NF) type 1 and 2 and Tuberous Sclerosis (TSC), Von Hippel Lindau disease and Li Fraumeni syndrome.

• Family History – If an immediate family member such as a sibling or parent has had a brain or spinal cord tumour, your risk of developing one is up to two times higher than the general population. The risk varies between subtypes of brain tumour.

Preventable risk factors

While the majority of brain tumours aren’t preventable, there are some environmental and lifestyle factors that influence risk.

• Obesity – Around 2% of brain and CNS tumours are related to obesity. The risk of developing a meningioma is around 60% higher in women who are obese.

• High birth weight – A birth weight of over 4kg is associated with conditions like gestational diabetes and is linked to a higher risk of primary brain and CNS tumours in childhood.

• HIV/AIDS – People with these conditions have an increased risk of developing CNS lymphoma due to a weakened immune system. Antiretroviral therapy can slow or reverse the progression of HIV and preserve the immune system, reducing the risk of this complication.

• Occupational exposure – Exposure to certain chemicals at work may increase the risk of developing brain cancer. These include non-arsenical insecticides, epichlorohydrin, inorganic lead, and chemicals used in petroleum refining. Workers in agriculture, rubber industries, and chemical manufacturing might be at higher risk due to these substances.

Does Radiation Cause Brain Cancer?

Yes, some forms of radiation can cause brain tumours. Ionising radiation, used in some radiological examinations like X-rays and radiation therapy has been linked to brain tumours.

• X rays and CT scans:  Less than 1% of brain and other CNS tumour cases in the UK are caused by ionising radiation. This includes X-rays, CT scans, and radiotherapy, which can increase the risk of developing brain and CNS tumours. Research has found that childhood CT scans can triple the risk of benign brain tumours, leukaemia, and other brain tumours.

However, these cancers are rare, translating to approximately a 0.01% (one in 10,000) chance of developing leukaemia or a brain tumour in the 10 years following the first scan for patients under 10. While the clinical benefits of CT scans often outweigh these risks, minimizing radiation doses and considering alternative, non-ionising procedures when appropriate is crucial to reduce potential harm.

• Radiotherapy: This treatment for childhood cancers is linked to a higher risk of gliomas and meningiomas later in life. Higher doses of radiation therapy are associated with a greater risk of developing brain and nervous system tumours. Yet, radiotherapy is only given in specific situations, usually as a lifesaving treatment where the benefits outweigh the risks.

Do Mobile Phones Cause Brain Tumours?

Mobile phones use radiofrequency (RF) signals, a form of non-ionising radiation that isn’t strong enough to damage DNA like X-rays or gamma rays, making their link to cancer unclear. Research on whether mobile phones are linked to a higher risk of brain cancer is inconclusive, and no clear link has been established.

Interestingly, some research has suggested a possible connection between an increased risk of primary brain tumours and long-term mobile phone use, but limitations in many of them prevent firm conclusions. Notably, mobile phones have only been widely used for about 20 years, so the long-term effects are unknown, especially for children and teenagers, whose usage patterns differ from adults.

Ultimately, it’s not possible to rule out the effects of mobile phones on brain cancer risk and research. If you want to reduce your exposure to RF signals, you can:

• Use speakerphone or earphones to keep the antenna as far from your head as possible
• Limit the length of calls
• Set a time limit on your daily phone use
• Text instead of calling.

Are brain tumours hereditary?

In some very rare cases, brain tumours can run in families, but these are related to specific and rare genetic conditions and genetic mutations, such as POT1 and HERC2. We know that having a first-degree or direct relative with a brain or CNS tumour increases your risk of developing cancer, but this doesn’t mean that there is a certainty of developing one. Unlike traits like hair or eye colour, brain tumours are not inherited in a straightforward way. The presence of these genetic factors only raises the likelihood, without guaranteeing the occurrence of brain tumours.

Putting your mind at ease

Understanding the risk factors for brain cancer can provide a sense of clarity and control during a challenging time. While many of these factors are beyond our control, being informed can help with early detection and management. Remember, a diagnosis of brain cancer is rarely due to anything you have or haven’t done.

At Gena, we’re committed to supporting you through your journey with comprehensive tools and resources. Our platform streamlines clinical trial enrolment, provides a free management tool for your clinical correspondence, and delivers digestible insights from genomic sequencing. Sign up with Gena to take control of your health and access these resources.

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