Children’s cancers are rarer than adult cancers, and they make up less than 1% of all cancers diagnosed each year. Childhood cancer is usually the result of a genetic mutation which causes cells to reproduce uncontrollably.

In most cancers, these changed cells begin to gather and produce tumours. Some childhood cancers, such as leukaemia, rarely result in tumours. Instead, cancer cells develop in the bloodstream and blood-forming organs.

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How does childhood cancer develop?

Most childhood cancers develop due to uncontrolled cell growth and changes in DNA that resulted from genetic mutations. These mutations are sometimes inherited from parents or result from events that occur either early in the child’s life or during foetal development. Many are likely to be caused by random events that happen inside a cell, without an external cause.

How does childhood cancer spread?

In cancers in which a tumour has formed, cells break away from the tumour and enter the bloodstream or lymphatic system to travel to other tissues or organs of the body and begin to multiply again to form more tumours. When cancer spreads from one organ or system to another, this is called metastasis.
In leukaemias, which are the most common childhood cancers, the cancer cells begin in the bloodstream and blood-forming organs and are carried to other tissues where they form tumours.

What causes childhood cancer?

Because childhood cancer is rare, and the cancers impacting are different to those found in adults, scientists are uncertain what causes the genetic mutations that lead to childhood cancers.
About 5 percent of the genetic mutations are inherited from parents. Other genetic mutations that cause childhood cancer may be attributable to events that occurred either early in life or during foetal development. For example, children with the genetic condition Down syndrome are 10-20 times more likely to develop leukaemia than children without Down syndrome.
It is extremely rare that childhood cancer is caused by external factors, such as exposure to radiation. Lifestyle factors usually take many years to have an impact on cancer risk, and it’s believed they do not play a role in childhood cancers.

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What different types of childhood cancer exist?

The types of cancers that occur most often in children are different from those seen in adults. Types of childhood cancer include: bone cancers, brain cancers, leukaemia, hepatoblastoma, lymphomas, neuroblastoma, retinoblastoma, rhabdoid tumours, sarcomas and Wilms’ tumours.
The most common types of childhood cancer include acute lymphocytic leukaemia, brain and other central nervous tumours, and neuroblastomas. These account for more than half of the diagnosed childhood cancers for children between the ages of 0-14 years.

Treating and preventing childhood cancer

How childhood cancer is treated depends on many factors including the type of cancer and how advanced it is. Treatments can include surgery, radiation, chemotherapy, immunotherapy, and stem cell transplant.

An emerging body of research is indicating that knowing a tumour’s genomic profile could be more important for successful treatment than knowing its location or size. As each tumour’s genomic profile is unique, this approach is often referred to as personalised or precision medicine.

Because none of the common childhood cancers are known to be caused by environmental or other external factors, it’s not yet known what can be done to prevent them. However, there is ongoing research studying the genetic origins of childhood cancer and how to improve cancer treatments.