Facts on the Condition
General description including types, causes, prevalence, signs and symptoms
Treatments, including role of specialists, effects of treatments, use of devices, daily routines
In general, cancer occurs when cells in the body multiply in an uncontrolled way. As their numbers increase, they form a mass that affects the normal functioning of the surrounding tissue. If cancer is not successfully treated at this stage, cancer cells can break away and spread through the bloodstream or lymphatic system to other parts of the body. This process is called metastasis. If a cancer metastasises it can be very difficult to treat or cure.
The cells in almost any part of the body can become cancerous. Cancers in children and young people are quite different from cancers affecting adults. They usually affect different parts of the body and the cancerous cells look different under a microscope. They are often treated with the same types of treatments but they respond differently, sometimes much better.
How common is childhood cancer?
Childhood cancer is much less common than adult cancers. In Australia about 500 children are diagnosed with cancer every year. Although this is significant, it is fewer in comparison with approximately 88,000 adults diagnosed with cancer each year. Cure rates for children are much higher than for most adult cancers with over 70% of all children now being cured. The figure can be as high as 90% for certain types.
What causes childhood cancer?
Cancer is caused by a disruption to a cell’s genes. In many adult cancers, this is clearly due to a carcinogen (an agent that causes cancer, like ultraviolet radiation or some of the substances in cigarettes). In most childhood cancers, the factors that cause cells’ genes to become abnormal have not been identified. Certain medical conditions, rare inherited disorders, exposure to radiation and previous cancer treatments have been linked to cancer, but the causes of most childhood cancers are not known. Scientists continue to study lifestyle and environmental factors in their search for a cause, but as yet have found none. We do know that cancer is NOT contagious. It cannot be passed from one person to another.
Cancer clusters
Although it is rare, two or three children/young people from the same school or community may develop cancer. This raises concerns that something in the local environment may be causing the cancer. When several people in one area develop cancer it is known as a ‘cancer cluster’. Cancer clusters are taken very seriously and investigated thoroughly. But usually it turns out that it is a coincidence rather than being caused by a particular environmental or chemical change.
Most common types of childhood cancer
Leukaemia is the most common form of cancer in children/young people, accounting for 30% of childhood cancer. It is a cancer of the white blood cells. In leukaemia, the primitive blood cells begin to multiply before reaching maturity. The rapid growth of the ‘leukaemia’ or abnormal cells causes them to out number the normal blood cells. There are different types of leukaemia.
Acute lymphoblastic leukaemia (ALL) is the most common form of leukaemia in children and young people. It accounts for 80% of childhood leukaemia. It starts in the bone marrow, the ‘factory’ where blood cells are made. Treatment is with chemotherapy (drugs that kill cancer cells) and in a small number of cases, radiotherapy (high energy waves similar to X-rays) to the brain. The cure rate is greater than 75%.
Acute myeloid leukaemia (AML) is a less common form of leukaemia in children/young people. It also occurs in the bone marrow. Treatment involves initial chemotherapy and, sometimes, stem cell transplantation. The cure rate is between 50 and 60%.
Brain tumours and spinal cord tumours are the second most common form of cancer in children and young people. They are more difficult to cure and cause the most deaths than any other type of childhood cancer. There are several different types of brain tumours. Treatment varies according to where the tumour is in the central nervous system. Surgery is the first line treatment for most brain tumours. Many people will also have follow up treatment with radiotherapy and chemotherapy. Survival rates vary depending on how early the tumour was diagnosed (the ‘stage’) and type of the tumour.
Less common types of childhood cancer
Lymphoma is cancer that starts in the lymphatic system. The lymphatic system is a system of thin tubes that run throughout the whole body (lymph vessels). Along these vessels are small glands known as ‘lymph nodes’. They branch into every part of the body except the brain and spinal cord. There are two types of lymphoma, Hodgkin’s disease and non-Hodgkin’s lymphoma. If caught in the early stages, both can be treated very successfully with chemotherapy.
Neuroblastoma is cancer that begins in the adrenal glands: the small glands just above each kidney. It may also start in nerve tissue in the neck, chest, abdomen or pelvis. Neuroblastoma generally occurs in children aged younger than five years. It is a serious cancer, particularly if it spreads through the bloodstream to the bone marrow. Treatment generally includes surgery, chemotherapy, radiotherapy and sometimes stem cell transplantation.
Bone tumours occur most often in adolescence, but can occur in younger children. The two most common types are osteosarcoma and Ewing’s sarcoma. They can begin in the pelvis, ribs or long bones of the arms or legs. Treatment is generally chemotherapy and surgery or occasionally radiotherapy (mainly for Ewing’s sarcoma). Where long bones are involved, amputation of the limb may be necessary. However, this is much less common now. Doctors will always try to use ‘limb sparing surgery’. This means removing the cancer, but not the arm or leg.
Retinoblastoma is a rare malignant tumour of the retina of the eye. It nearly always affects children under the age of 5. It accounts for around five per cent of childhood blindness. Although this type of cancer is very frightening for the child and their parents in most cases, with the right treatment, it can be cured.
Rhabdomyosarcoma is a type of cancer that grows in muscle. These cancers can form anywhere in the body and there are several types. They may spread through the bloodstream to the lungs, making the prognosis less hopeful. The main treatment is surgery to remove the tumour. You may also have chemotherapy or radiotherapy before surgery to help shrink the cancer and make surgery easier. Or you may have these treatments after surgery to help reduce the chance of the cancer coming back. In rare cases a rhabdomyosarcoma can occur in places where they cannot be completely taken out using surgery. If this happens then a combination of radiotherapy and chemotherapy is given to kill the cancer
Wilms’ tumour is a cancer of the kidney that occurs most often in children aged younger than five years. You may also hear them called ‘nephroblastomas’. Nearly all tumours found on the kidneys in children are Wilm’s tumours. These tumours were one of the first childhood cancers where cure was possible. Even if the tumour has spread through the bloodstream to the lungs, the outlook is excellent.
The tumour can begin to develop in a baby when it is still growing inside its mother. But it may not cause any symptoms until the child is a few years old. Wilm’s tumours usually only affect one kidney (unilateral) but in about 7% of cases it can affect both (bilateral).
Treatment is by surgical removal of the affected kidney, chemotherapy and sometimes radiotherapy. It is possible to live a normal life with one kidney.
There are other rarer types of cancers that affect children and young people. For example, thyroid cancer and ovarian teratomas. For more information about any type of childhood cancer you can contact your local Cancer Information and Support Service on 13 11 20.