Cancer is a disease that occurs when abnormal cells in the body grow in an uncontrolled way. The types of cancers that occur in children, and the way they respond to treatment, can be different to cancers that occur in adolescents or adults.
This section provides information on children’s cancer, its causes, the most common cancer types and general signs and symptoms.
On this website, a child is defined as a person aged less than 15 years.
The types of cancers that occur in children, and the way they respond to treatment, can be different from cancers that occur in adults. They can also be different from the types of cancers that occur in adolescents and young adults (aged 15–29 years) – there are often specific protocols and guidelines for the management of adolescents and young adults with cancer, which bridge the gap between children’s cancers and adult cancers.
What is cancer?
Cancer is a disease of the cells, which are the body’s basic building blocks. Cancer occurs when one cell becomes abnormal, and starts to grow and multiply in an uncontrolled way. These abnormal cells damage or invade the surrounding tissues, and often spread to other parts of the body, causing further damage.
Cells in our bodies divide and form new cells all the time to replace old, worn-out cells. This lets us grow and repair damaged tissues (such as on the surface of our skin or in the gut).
Occasionally, an abnormal cell keeps dividing in an uncontrolled way and forms a lump (called a tumour). Some tumours grow only in one place, do not invade surrounding tissues and do not spread to other parts of the body. These are called ‘benign’ tumours.
Cancer refers to a type of tumour called a ‘malignant’ tumour. These tumours can destroy normal cells, and invade and damage surrounding healthy tissues. The site (part of the body) where the tumour starts is called the primary site, and the tumour at this site is called the primary tumour. Cells from malignant tumours can escape from the primary tumour and spread to other parts of the body to form new tumours in those sites. These new tumours are called secondary tumours or metastases.
Cancer is not one disease. It is a word used to describe a number of different diseases that affect different cells and tissues in the body, behave in different ways, and respond differently to treatments.
Children’s cancers are often very different from cancers that occur in adults. They can look different under the microscope, occur in different parts of the body and respond differently to treatment.
Childhood cancers can be the result of DNA (genetic) changes in cells that take place very early in life, sometimes even before birth. Unlike many cancers in adults, childhood cancers are not strongly linked to lifestyle or the environment.
What causes cancer in children?
It’s not always clear why some people get cancer and some don’t.
Anything that is associated with increasing someone’s chance of developing cancer is called a risk factor. The risk of getting some cancers, particularly in adults, is related to environmental factors (such as smoking or exposure to certain chemicals), lifestyle (such as drinking alcohol or spending too much time in the sun) or some viral infections (such as human papillomavirus infection, which can cause cervical cancer). The risk of getting certain cancers (e.g. breast cancer) is also higher in some families than others.
In most cases, we don’t know why children get cancer. Children are too young to have the same risk factors that affect adults (e.g. environmental exposures, lifestyle, infections). Tumours occasionally develop as a result of a genetic error made in children’s growing bodies.
Cancer is not caused by accidents such as a bump on the head, or by anything the child or their parents did or did not do. Cancer cannot be passed from one child to another like chickenpox or the flu.
In children, age is not a risk factor for cancer, but the incidence of some cancers varies with age. Some childhood cancers tend to appear in very young children and others in older children. Family history is also important because a few childhood cancers run in families.
Even if your child has a risk factor, it does not mean they will develop cancer. Many children with a risk factor will never develop cancer, while others with cancer may have had no known risk factors. Even if a person with a risk factor develops cancer, it is usually hard to know how much that risk factor contributed to the development of their disease.
How common is childhood cancer?
In 2015, it is estimated that 650 Australian children will be diagnosed with cancer. It is a significant health issue.
Find out more about Children's Cancer statistics in Australia.
What types of cancer affect children?
In children, cancer tends to affect fast-growing tissues such as blood, lymph, bone marrow, nervous tissues, muscles, kidney, liver and bone. Specific information on the types of cancers that affect children can be found in the Types of Children's Cancers section.
What are the signs that a child might have cancer?
Children’s cancers are difficult to diagnose because many of the symptoms are the same as those that occur in common and less serious illnesses, such as a cold, or may appear as bumps and bruises. Symptoms and signs of cancer can include:
- easy bruising, or bruising that doesn’t go away
- an unusual lump, bump or swelling
- unexplained paleness, tiredness, loss of energy and loss of interest in things
- pain in one area of the body that doesn’t go away
- limping or difficulties moving around
- unexplained fever or illness that doesn’t go away
- frequent headaches, often with nausea or vomiting
- visual changes, such as blurred vision
- unexplained weight loss.
If your child has any of these symptoms, it does not mean that they have cancer. However, if your child has any or some of the above symptoms that do not go away quickly, it is important to have a check-up with your local general practitioner (GP). If the GP thinks the symptoms might be caused by cancer, they will refer your child to a specialist for more tests such as blood tests, urine tests, X-rays or other medical imaging scans.
Will my child get better?
Many children with cancer are cured of the disease. Children’s bodies have great capacity for healing. Also, huge improvements have been made in the treatment of childhood cancer in the past few decades. In the 1980s, around 65% of children diagnosed with cancer were alive more than 5 years after their diagnosis. Today, around 83% of children are successfully treated and become long-term survivors.
Many children who are cancer survivors can expect to live as long as children in the general population, and being a childhood cancer survivor does not substantially affect a child’s prospects for a long life. This includes children who have a poor prognosis when they are diagnosed – 5 years after a cancer diagnosis, most children have a similar survival rate to children who have not had cancer.
In Australia, virtually all children with cancer are treated at specialised centres that are designed for them. These centres are staffed by a team of specialists who know the differences between adult and childhood cancers, and understand the unique needs of children with cancer and their families.
There are two types of treatment for cancer – curative, where the aim is to destroy the cancer and cure the disease, and palliative, where the aim is to minimise pain and maximise quality of life for patients whose cancer can’t be cured. This website deals with the curative aspects of cancer in children.
- Cancer Council Victoria. Diagnosing children’s cancers (accessed December 2014).
- Paediatric Integrated Cancer Service. What is cancer? (accessed December 2014).
- Women’s and Children’s Health Network. Kids Health – What is cancer? (accessed December 2014).
- Women’s and Children’s Hospital Adelaide. Childhood cancer: information for your family (accessed December 2014).
- Youlden DR, Baade PD, Hallahan AR, Valery PC, Green AC, Aitken JF. Conditional survival estimates for childhood cancer in Australia, 2002–2011: a population-based study. Cancer Epidemiol. 2015 Jun;39(3):394-400.