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Risk factors for brain and spinal cord cancer
A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. But sometimes brain and spinal cord cancer develops in people who don’t have any of the risk factors described below.
The number of brain tumours diagnosed each year has been increasing since the 1970s. Researchers think this is because we are now better at diagnosing and collecting data on brain tumours.
Most types of brain and spinal tumours develop in men more often than in women. Only meningiomas are more common in women than in men. A number of these tumours occur in childhood, and then rates of brain and spinal cord cancer increase again in people in their 20s. Rates tend to be lower in people 70 years of age and older.
Risk factors are generally listed in order from most to least important. In most cases, it is impossible to rank them with absolute certainty.
*You may wonder about alcohol and polio vaccines. There is significant evidence showing that there is no association between these factors and brain and spinal cord cancer.
Known risk factors
There is convincing evidence that the following factors increase your risk for brain and spinal cord cancer.
Researchers have shown that radiation to the head increases the risk of developing brain tumours. Adults who have radiation to treat non-cancerous, or benign, brain tumours have a higher risk of developing another brain tumour. People who were treated with radiation to the head when they were children also have a higher risk for developing a brain tumour. They may have had radiation to treat childhood leukemia, scalp ringworm (tinea capitis) or birthmarks on the face.
Studies have shown that people who were exposed to radiation from the atomic bombs in Hiroshima and Nagasaki have a higher risk for different types of brain tumours.
Brain tumours are more common in people who have had medical radiation. Medical radiation includes CT scans, dental x-rays and other x-rays to the head. Radiation doses from medical radiation were higher in the past. It is important to remember that CT scans and x-rays help diagnose illness and make sure you have the right treatment. Doctors will order these tests when they think you need them and they will keep your exposure to medical radiation as low as possible.
An inherited, or genetic, condition is passed from parents to their children through genes. People with the following inherited conditions have a higher risk of developing brain and spinal cord tumours:
Neurofibromatosis (NF) affects the nerves, muscles, bones and skin. Both neurofibromatosis type 1 (von Recklinghausen disease, or NF1) and neurofibromatosis type 2 (acoustic neuroma, or NF2) increase the risk for brain and spinal cord cancer. But these cancers occur more often in people with NF1. Some research shows that brain and spinal tumours caused by NF2 tend to be slow-growing and non-cancerous.
Von Hippel-Lindau syndrome
Von Hippel-Lindau (VHL) syndrome is rare. It makes blood vessels grow into knots called angiomas. These knots occur in parts of the body that are rich in blood vessels, such as the brain, spinal cord and adrenal glands.
Li-Fraumeni syndrome increases the risk of developing a number of different types of cancer, including brain tumours.
Tuberous sclerosis is also called Bourneville’s disease. It causes non-cancerous tumours to develop in the brain and spinal cord, skin, heart or kidneys.
Turcot syndrome causes multiple growths, called polyps, in the colon. It also causes tumours of the brain and spinal cord.
Basal cell nevus syndrome
Basal cell nevus syndrome is also called Gorlin syndrome or nevoid basal cell carcinoma syndrome. It causes problems with several organs and increases the risk of developing different types of tumours, including brain and spinal cord tumours.
Cowden syndrome causes many hamartomas to develop in the skin, breast, thyroid, colon, small intestine and mouth. Hamartomas are non-cancerous tumour-like nodules, or lumps.
A family history of brain tumours means that one or more close blood relatives have or had a brain tumour. Some families have more cases of brain tumours than would be expected by chance. Sometimes it is not clear if the family’s pattern of brain tumours is due to chance, shared lifestyle factors, an inherited risk factor that has been passed from parents to children through genes or a combination of these factors.
Find out more about inherited cancer risk.
People who had cancer as a child have a higher risk of developing a brain tumour later in life. Researchers have linked this higher risk for a brain tumour to the treatment used for the childhood cancer. For example, radiation therapy to the head can increase the risk for a brain tumour later in life. Adults who received methotrexate as chemotherapy given directly into the brain (called intrathecal chemotherapy) to treat childhood leukemia also have a higher risk for brain tumours.
It is important to remember that the increase in risk for a brain tumour from treatment is small compared to the risk of not treating the original cancer.
The immune system is a complex group of cells and organs that defends your body against infection, disease and foreign substances. When the immune system isn’t working well, you are at greater risk for primary central nervous system lymphoma (PCNSL). People at high risk include those who:
- take drugs to suppress their immune system after an organ transplant
- have treatment, such as chemotherapy, that suppresses their immune system to treat other cancers
- have HIV or AIDS
Using cellphones is a possible risk factor for brain and spinal cord cancer. This means that it has been linked with brain and spinal cord cancer, but there is not enough evidence to show it is a known risk factor.
Cellphones give off radiofrequency radiation, which is a form of non-ionizing electromagnetic radiation. Tissues closest to where the phone is held can absorb this radiation. A small number of studies have shown a link between using cellphones and brain and spinal cord cancer. Most scientific research does not show this link. Further study is needed to clarify the role of using cellphones for brain and spinal cord cancer.
Unknown risk factors
It isn’t known whether or not the following factors are linked with brain and spinal cancer. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if the following are risk factors for brain and spinal cancer.
Exposure to vinyl chloride, solvents, petroleum, coal products, polychlorinated biphenyls, pesticides, anesthetics or certain pharmaceuticals might increase the risk for brain and spinal cord cancer. Jobs in petrochemical, refining, rubber, lumber, farming, electrical and healthcare industries may expose you to these substances.
Engineers, lawyers, judges, doctors, veterinarians, managers, administrators, business and repair services employees, and butchers and meat cutters may be at higher risk for brain and spinal cord cancers. They may be exposed to an unspecified factor that increases their risk.
The following are also unknown risk factors for brain and spinal cord cancer:
- exposure to electromagnetic fields
- infections that weaken the immune system (for example, infection with Epstein-Barr virus or human cytomegalovirus)
- trauma to the head
- medical conditions including epilepsy, multiple sclerosis and stroke
- breast cancer
- smoking and environmental tobacco smoke
- diet (for example, eating cured meats or taking too many vitamin supplements)
- contaminants in drinking water (for example, nitrite, chlorine or disinfection by-products)
- hair dye
- tall adult height
Questions to ask your healthcare team
To make the decisions that are right for you, ask your healthcare team questions about risks.