What is cancer?
Statistics show that 1 in 2 men and 1 in 3 women will be diagnosed with cancer!
Cancer is not a single disease with a single cause or type of treatment. There are more than 200 types of
cancer, each with its own name, behaviour and treatment.
Cells and genes
The organs and tissues of the body are made up of cells. Each cell has a nucleus, or control centre,
containing coded instructions called genes. The genes tell the cell what type of cell it should be, e.g. skin,
bone or blood. The genes also tell the cells when to divide and replicate themselves in an orderly and
controlled manner and how to repair damage done through everyday living.
All kinds of cancer, including childhood cancer, develop when the genes that normally keep our cells
healthy develop a fault.
Genes act as control mechanisms to stop cells dividing too much. However, in abnormal or faulty cells the
control mechanisms do not work, and the cell divides uncontrollably, developing into a lump or cluster of
cells which is called a tumour.
Some tumours are benign or harmless because they do not invade the surrounding tissues or spread to
other parts of the body. Therefore they are not cancerous, and may not need treatment. But malignant
tumours – the cancers – have the ability to spread (metastasize) beyond the original site to other organs
and tissues via the bloodstream or lymphatic system, and require treatment. These cells may continue
reproducing in the new site forming a new tumour. For example, a woman originally diagnosed with breast
cancer may later develop a secondary cancer in her lungs.
About 300 children in the UK develop brain tumours each year, with boys being affected more than girls.
Brain cancers are the second most common cancer found in children and young people under the age of
A scan of a brain with a tumour
Brain tumours can develop from any of the different types of cells found in the brain. Most brain tumours are
benign, which means they do not spread into other areas of the brain. Malignant brain tumours can spread
to the normal brain tissue which surrounds them. This can cause damage to the surrounding areas and
increase pressure inside the skull and on the nerves.
The two main types of brain tumours that affect children are astrocytoma and medulloblastoma.
Astrocytoma develops from the astrocytes, cells which support the structure of the brain and hold nerve
cells in place. Medulloblastoma develops in the cerebellum, a region at the back of the brain. These
cancers may spread to other parts of the brain or into the spinal cord.
Surgery is usually used to treat brain tumours. If necessary, the surgery may then be followed by
chemotherapy and radiotherapy.
Causes of cancer
What causes cancer in an individual varies from cancer to cancer, and from person to person. The most
common causes of cancer are environmental factors such as smoking, sun damage, diet or viruses. A
less common cause is genetic factors, when genetic faults are inherited from our relatives.
The other pages in this section provide more detail on the main cancers that occur in children and young
Reduce the risk
The risk of developing cancer varies from person to person – everything from age and lifestyle to genetics
and our environment play a part.
The part we have most control over is our lifestyle – eating healthily, not smoking, drinking alcohol in
moderation, taking regular exercise and protecting ourselves from the sun.
We’ve included this information in an engaging way for children and young people on our Why Bother youth
Here are the five basic principles to communicate to young people:
Stop smoking. More than 120,000 people a year in the UK die from smoking-related diseases such as
cancer, asthma and chronic heart disease. Most of these people started to smoke while they were at
school. Smoking shortens life span by 10 years or more, and it’s also a very expensive habit – costing up
to thousands of pounds a year.
Your pupils or students may be interested in the animated movie on the effects of Smoking on our Why
Bother youth website.
Take regular exercise. You should try to maintain an even balance between the energy you get from the
food and drink you consume and the energy you burn through activity. Aerobic activity increases your heart
rate, promotes good circulation and oxygen levels and keeps the heart, the most important muscle in the
body, exercised. You should aim for at least two hours in total per week.
Drink and eat healthily. Drinking too much alcohol is hard on your immune system. Remember to stay
hydrated too – the body needs plenty of water to function properly. A balanced diet helps you stay healthy.
Be careful in the sun. The sun is a main source of vitamin D, but its powerful rays can damage your skin
and cause skin cancer. To be safe in the sun and protect yourself from harmful ultraviolet (UV) rays, stay in
the shade between 11am and 3pm when the sun’s rays are strongest. Seek shade, wear a protective hat,
clothing and sunglasses. Use sunscreen with at least a factor of 15 or higher. Sunbeds carry the same
risks, so for a ‘safe’ tan that saves your skin and possibly your life, use fake tan.
Be body aware. The most important thing to remember is that the earlier a cancer is diagnosed, the
sooner it can be treated, and the better the chance of recovery. Know your body, be aware of any changes
and go to your doctor if you notice any unexplained changes.
Most common types
Cancer in children and young people is rare – no one knows how children and young people get cancer.
Cancer in children and young people is more likely to be in developing organs and systems – such as in
the blood, bones and nervous system – than in organs such as lungs.
The most common childhood cancer is leukaemia, which accounts for about a third of all cases. Brain and
spinal tumours are the second most common type of cancer in children and young people – they account
for about a quarter of all cases. The chart below shows the percentages of types of cancers affecting
children in the UK (from Cancer Research UK, December 2004).
Did you know?
Cancer is the most common cause of non-accidental death in young children, teens and young adults in
1 in 330 boys and 1 in 420 girls will develop cancer before their 20th birthday
In the last 30 years the incidence of cancer in the teenage and young adult group has increased by 50%
and for the first time ever, the number of teens with cancer now exceeds the number of children with cancer
About one-third of all children and young people with cancer in the UK are diagnosed with leukaemia.
There are nearly 400 new cases diagnosed each year in the UK.
The term ‘leukaemia’ refers to cancers of the white blood cells. When someone has leukaemia, large
numbers of abnormal white blood cells are produced in the bone marrow. These abnormal white blood
cells crowd the bone marrow and flood the bloodstream. Initially leukaemia cells appear only in the bone
marrow and blood, but later they may spread elsewhere.
On our youth website we’ve included a simpler explanation, with more information about symptoms and
Common types of leukemia in children and young people
Leukaemia is either acute (rapidly developing) or chronic (slowly developing). The types of leukaemia most
likely to occur in children and teens are acute lymphocytic leukaemia (ALL) and acute myelogenous
Chemotherapy is the main treatment for this type of cancer.
Acute lymphocytic leukaemia (ALL) is a type of leukaemia that involves a particular sort of white blood cells
called lymphocytes. ALL is more common in boys than girls. It is also known as acute lymphoblastic
Acute non-lymphoblastic leukemia (ANLL) is a type of leukaemia that does not involve lymphocytes. It is
also known as acute myeloid leukaemia (AML) because the cancerous cells are myeloid white blood cells.
Chemotherapy is usually the main treatment for this type of cancer, although in some cases radiotherapy
is also used.
The term ‘lymphoma’ refers to cancers of white blood cells (lymphocytes) that travel around the body in
Lymph is a clear fluid that carries food to cells and takes waste materials away via the lymphatic system
(see diagram). It also contains lymphocytes, which the body uses to fight infection.
The lymphatic system
Although many other types of cancer eventually spread to parts of the lymphatic system, lymphomas are
distinct because they originate there. Lymphomas are more than twice as common in boys as in girls, and
very rarely occur before the age of two.
Common types of lymphoma in children and young people
There are about 20 different types of lymphoma, but the most common are Hodgkin’s disease (named
after Dr Hodgkin, who first described it) and non-Hodgkin’s lymphoma.
There are about 20 different types of lymphoma, but the most common are Hodgkin’s disease and non-
Hodgkin’s disease is more common in teens than children, and is defined by the presence of specific
cancerous cells, called ‘Reed-Sternberg cells’, found in the lymph nodes or another part of the lymphatic
system. Chemotherapy, radiotherapy or a combination of the two are usually used to treat this type of
Non-Hodgkin’s lymphoma (NHL) is more common than Hodgkin’s disease and affects both children and
young people. It is different from Hodgkin’s disease because ‘Reed-Sternberg cells’ are not found in this
type of lymphoma. This means that doctors treat the cancer slightly differently. Chemotherapy is usually the
main treatment for this type of cancer.
A sarcoma is a malignant tumour that arises from the bone cells (bone sarcoma) and soft tissues (soft
tissue sarcoma) that form the supporting structures of the body, such as muscle tissue. These tumours
There are two common types of bone sarcoma – Osteosarcoma and Ewing’s sarcoma. Osteosarcoma is
more common than Ewing’s sarcoma and typically develops in fast-growing long bones, such as those in
the legs and arms.
Ewing’s sarcoma is less common and although it can develop in long bones, it typically develops in short
bones, such as pelvis and shin bone. Surgery, chemotherapy, and radiotherapy may all be used to treat
this type of cancer, though in the past amputation of an affected limb was the main treatment.
Soft tissue sarcoma
This type of sarcoma occurs in the soft supporting structures of the body such as ligaments, muscle, and
tendons and can spread to other parts of the body. Rhabdomyosarcoma is the most common type of soft
tissue sarcoma found in children and young people.
Surgery is usually used to treat this type of cancer. The surgery may also be followed by chemotherapy and
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