About children's cancer

What is cancer?

Cancer is a disease of the body’s cells. 
Cells are the building blocks of the body. As cells die off or wear out, new cells replace them. 

With cancer, the growth of new cells becomes faulty. The abnormal cancer cells multiply out of control.

The abnormal cells can affect the body in different ways.

• Tumours (e.g. brain tumours): The abnormal cells can form a lump (tumour). Tumours cause medical problems in two ways:
  • Directly, by pressing on and damaging nearby organs.
  • Indirectly, by breaking off and invading other distant tissues and organs.
• Blood (e.g. leukaemia): When cancer affects blood cells, abnormal blood cells build up in the bone marrow or blood. This can affect the way your body normally works and cause symptoms.
• Lymphatic system (e.g. lymphoma): The lymphatic system is part of our immune system, which protects us from infection and disease and removes extra fluid and waste from the body’s tissues. It is made up of lymph nodes connected by tiny tubes called lymph vessels. Lymphoma cancers happen when lymphocyte white blood cells grow in an abnormal way. The abnormal cells collect in your lymphatic system, particularly the lymph nodes. This causes swellings, known as lymphomas.
• Cancer is a word for many different diseases
  There are more than 200 types of cancer that affect different parts of the body in various ways and which need different treatments.
• Cancers sometimes spread
  If a tumour is cancerous (malignant), a cell or group of cells can be carried by your blood or lymph fluid to another part of your body, where it can form a new (secondary) tumour. This is called metastasis. 

Why do children's cancers happen?

The cause of most children's cancers is unknown, but there are certain factors that may increase the risk of certain cancers developing. 

Unfortunately, there is nothing a parent can do to prevent childhood cancer, as the risk factors linked to childhood cancers are not things we can control.   

Having a risk factor doesn’t mean your child will definitely get cancer. Often children with no risk factors get the disease. 

If you feel your child may be at risk, first talk to your family doctor (GP) about your concerns. He or she may advise you to visit a specialist. 

Risk factors for children's cancer

• Inherited medical conditions. Children with inherited conditions such as Down syndrome are more at risk of developing childhood leukaemia, but it is still very rare. 
• Development in the womb. Rarer tumours such as Wilms tumour and retinoblastomas are believed to develop while the child is still in the womb. 
• Infection. Epstein Barr virus (EBV) is a common infection among children. It is thought that EBV can contribute to the development of certain types of lymphoma. 
• Previous cancer treatment radiotherapy. Children who have been treated with radiotherapy or chemotherapy for cancer in the past have a slightly higher risk of getting another cancer in the future

What kinds of cancer affect children?

It is rare for children to get cancer. Children's cancers affect approximately 170 children and teenagers under the age of 15 each year in Ireland. The most common cancers that affect children are: 

• Leukaemia. Cancer of the white blood cells, which help us to fight infection. About 1 in every 3 cancers that affects children is leukaemia. There are two  main types of leukaemia, acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia(AML).
• Brain tumours. Cancer that causes a tumour (lump of abnormal cells) in the brain. The brain, together with the spinal cord, controls all the functions of the body. Some are benign (not cancer), while others are malignant (cancer). The most common types are astrocytoma, medulloblastoma and ependymoma.
• Sarcoma. Cancer affecting muscles or bone. They include soft tissue sarcomas, rhabdomyosarcoma and bone tumours, such as Ewing sarcoma and osteosarcoma.
• Germ cell tumour. Cancer that affects the cells that make eggs (in a girl’s ovaries) or sperm (in a boy’s testicles).
• Lymphoma. Cancer of the lymphatic system, which is part of your immune system. There are two main types: Hodgkin and non-Hodgkin lymphoma.
• Liver cancer. Cancer that affects the liver. The liver helps blood to clot, breaks down fats and carbohydrates from our food and gets rid of harmful substances from our body. The most common types of malignant tumours in the liver are hepatoblastoma and hepatocellular carcinoma.
• Neuroblastoma. Cancer that affects nerve cells called neuroblasts . It occurs either in the nervous system or adrenal glands. It is usually located in the abdomen but can occur anywhere in the body.
• Retinoblastoma. A rare cancer that causes a tumour in the eye. 
• Renal tumour (kidney). Cancer that affects the kidney. The kidneys filter your blood to remove waste products. The most common type that affects children is called Wilms’ tumour. It is also called nephroblastoma.
• Other epithelial and melanomas. Includes rare tumours of the head and neck  (nasopharyngeal carcinoma) and the skin (melanoma).

Children's cancer tends to occur in different parts of the body to adult cancers. They also look different under the microscope and respond differently to treatment. Cure rates for children are much higher than for most adult cancers. 

On average more than 8 out of 10 children in Ireland will survive their cancer for 5 years or more.