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Risks and causes of cancer in children

Parents of children with cancer can sometimes feel like something they did, or didn’t do, caused their child’s cancer. We don’t know what causes, or how to prevent most childhood cancers and no one should feel blamed.

Although we have identified a number of lifestyle changes that can help to reduce the risk of adults developing cancer, it doesn’t look like there is anything we can do to prevent most childhood cancers.

Cancer is not infectious. You can’t catch it from another person and your child can’t pass it on to their siblings or other children in their school. It is unlikely for 2 children in one family to be diagnosed with childhood cancer.

Risk factors for children’s cancers are not well understood. This is because this group of cancers are relatively rare and there are lots of different types. This makes them difficult for researchers to study. But we know there are some factors that can increase the risk. While the factors listed below are linked to children’s cancers, most children with cancer aren’t affected by any of them. And many children who are affected by these risk factors won't go on to develop cancer.

Known risk factors

These include:

  • medical conditions
  • problems with development in the womb
  • exposure to infections
  • exposure to radiation
  • previous cancer treatments

Medical conditions

Certain conditions can increase a child's risk of developing some types of cancers.

For example, children with Down's syndrome are 10 to 20 times more likely to get leukaemia than other children. Leukaemia is still very rare, even in children with Down’s syndrome.


Retinoblastoma is a rare type of eye cancer. Some children are born with a change (mutation) in the retinoblastoma gene, also known as the RB1 gene. This may be because they inherited the gene from one of their parents, or because a change happened to this gene during the very early stages of their development in the womb. Most children who have a change to the RB1 gene develop retinoblastoma. About 4 out of 10 children diagnosed (40%) have this inheritable type of retinoblastoma, which often affects both eyes.

Some other childhood cancers, such as Wilms’ tumour, may have a genetic link, but the link isn’t as clear as with retinoblastoma.

Problems with development in the womb

Some childhood cancers such as Wilm’s tumours (kidney cancer in children) and retinoblastomas (eye cancer in children) begin when the baby is still inside their mother.

When a baby is growing in the womb, many parts of the body, such as the kidneys and eyes, develop very early on. Sometimes something goes wrong and some of the cells that should have turned into mature cells to form a part of the body don’t. Instead they remain as very immature cells.

Usually, these immature cells don't cause any problems and mature by themselves by the time the child is 3 or 4. But if they don’t, they may begin to grow out of control and develop into a cancerous tumour.

Exposure to infections

Epstein Barr virus (EBV) is a common infection in young children. It usually causes no symptoms. But, it can cause glandular fever (infectious mononucleosis) in teenagers and young adults. While glandular fever can be very unpleasant, it usually passes within a few weeks and it doesn’t mean that you go on to develop cancer. Once infected, a person remains a carrier of EBV for life, but the virus normally doesn’t cause any symptoms at all.

In rare cases, infection with EBV can contribute to the development of cancers such as Hodgkin lymphoma and Burkitt’s lymphoma.

Most people get infected with EBV as a child and stay infected for life without ever experiencing any symptoms. Because of how common it is, there is nothing you can do to prevent you, or your child, coming into contact with EBV at the moment.

Exposure to radiation

Radiotherapy is used as a treatment for cancer. It uses a type of radiation called ionising radiation. Children who have radiotherapy for cancer have a slightly greater risk of developing another type of cancer later on. But the risk is small compared to the risk to their health if the original cancer had not been treated with radiotherapy.

Radon gas is a natural radioactive gas and it is a type of ionising radiation. Radon gas is found in the air at a low level outdoors, but it can sometimes build up to high concentrations indoors. Because it is a natural gas, it is difficult or us to control our exposure to it. Overall, studies so far have only suggested that there might be a weak link between indoor levels of radon gas and risk of childhood leukaemia.

Previous cancer treatments

Past treatment with chemotherapy can increase the risk of cancers such as acute leukaemia many years later in children and adults.

Last reviewed: 
25 Jan 2018
  • Children's cancer statistics: Cancer Research UK (Cancer Stats)

    Accessed 2017

  • Risks of leukaemia and solid tumours in individuals with Down's syndrome

    H Hasle and others

    The Lancet, 2000

    Volume 355, Issue 9199

  • Screening Children at Risk for Retinoblastoma: Consensus Report from the American Association of Ophthalmic Oncologists and Pathologists

    AH Skalet and others

    Opthalmology, 2017

    Available online ahead of print

  • Epidemiology of Childhood Cancer

    J Little, 1999

    Lyon: IARC press

  • Second cancers in survivors of childhood cancer

    S Bhatia and C Sklar

    Nature Reviews Cancer, 2002

    Volume 2, Issue 2

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact with details of the particular risk or cause you are interested in.



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