Cancer risk refers to a child's risk of developing cancer. Any substance or condition that increases the risk of cancer is referred to as a risk factor.
There isn't a known single cause of childhood brain and spinal cord cancer. Most cancers are the result of many risk factors. However, some children with brain and spinal cord cancer do not have any identifiable risk factors.
Note: For purposes of readability, further references to brain cancer or brain tumour will automatically mean brain and spinal cord cancer or brain and spinal cord tumour.
*Risk factors are generally listed in order from most significant to least significant. In most cases, it is impossible to rank the relative significance of individual risk factors with absolute certainty.
There is a peak in incidence of brain and spinal cord cancer during the first 10 years of life, with many cases developing within the first 2 to 3 years. Boys are more likely than girls to develop a medulloblastoma, ependymoma or germ cell tumour. All other tumour types develop equally among boys and girls.
The following factors are known to increase the risk of developing childhood brain and spinal cord cancer.
Genetic conditions
Some children have a genetic condition that places them at a higher risk for developing a brain tumour. This is rare and occurs in less than 10% (fewer than 1 in 10) of children with brain tumours. Genetic disorders that may place a child at risk for a brain tumour include:
- neurofibromatosis type 1 (von Recklinghausen disease)
- Changes in the NF1 gene are responsible for this condition.
- This is the most common genetic disorder to increase the risk of brain tumours.
- This condition may be linked to optic nerve glioma, other gliomas of the brain and spinal cord, and neurofibromas (benign tumours of the peripheral nerves).
- neurofibromatosis type 2
- Changes in the NF2 gene are responsible for this condition.
- Type 2 is less common than type 1.
- This condition is associated with an increased risk for acoustic and peripheral schwannoma, meningioma and spinal ependymoma.
- Li-Fraumeni syndrome
- Changes in the TP53 gene are responsible for this syndrome.
- This condition is associated with an increased risk for medulloblastoma, astrocytoma and primitive neuroectodermal tumours (PNET).
- tuberous sclerosis
- Changes in the TSC1 or TSC2 genes are responsible for this condition.
- This condition is associated with an increased risk for subependymal giant cell astrocytoma as well as other benign tumours of the brain, skin, heart or kidneys.
- von Hippel-Lindau disease
- Changes in the VHL gene are responsible for this condition.
- This condition is associated with an increased risk for hemangiomas (blood vessel tumours) in the brain, spinal cord, retina and kidney.
- Turcot syndrome
- Changes to the APC gene are responsible for this syndrome.
- This condition is associated with an increased risk for medulloblastoma (most common), astrocytoma and ependymoma (less common).
- nevoid basal cell carcinoma
- This condition is associated with an increased risk for medulloblastoma or meningioma.
- other genetic conditions
- ataxia-telangiectasia
- Cowden syndrome
- Gorlin syndrome (nevoid basal cell carcinoma syndrome)
- hereditary retinoblastoma
- Rubenstein-Taybi syndrome
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Prior radiation to the head
Children who received radiation to the head for an earlier cancer or for treatment of tinea capitis (a fungal infection of the scalp) have an increased risk of developing a brain tumour later on in adulthood.
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Unknown risk factors
The following are factors for which there is not enough evidence or the evidence is inconclusive. In other words, it can't be determined for sure whether these risk factors are or are not associated with childhood brain cancer.
- environmental factors – Environmental factors have been suggested to increase the risk of childhood brain tumour development. However, research is limited and there is no conclusive evidence to show that exposure to the following factors increases the risk:
- electric and magnetic fields, such as power lines and electronic devices
- paint and solvents
- agricultural pesticides
- parents' occupational exposure
- mothers' prenatal diet
- child's diet
- father's smoking habits
- certain viruses/infections
- cell phones
- head injury – Head injuries do not appear to cause brain tumours in children. However, investigation of a head injury may draw attention to a pre-existing brain tumour.
- family history – There are some reports that show no association between a family history of cancer and childhood brain cancer, while other reports show an increased risk of brain tumours in families with a history of leukemia, lymphoma or bone cancer. Children or siblings of people with cancer may be at higher risk. More research is necessary before family history of cancer can be considered a known risk factor.
- birth weight – Infants who weigh more than 4000 grams (8.8 lbs) at birth may be at increased risk for brain tumour development, especially astrocytoma and medulloblastoma.
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See a list of questions to ask your doctor about risks.