What is cancer?
Cancer is a disease that's caused by cells in the body growing out of control and making new abnormal cells.
Every part of our body is made up of cells that fit together like building blocks. Cells of the same type group together to make different kinds of tissue, for example fat, muscle, bone, nerves and blood (a liquid tissue).
Each cell has a control centre (called a nucleus) where DNA (deoxyribonucleic acid) is stored. The nucleus tells the cell what to do and contains our genes (which we inherit from our parents).
Cells are too small to see with your eye, but doctors can examine them with powerful microscopes and tell what type they are.
Usually cells grow, divide to make new cells, and eventually die off. Millions of cells die every second, but millions of others divide to replace them.
Cancer develops when something goes wrong with the cell and it grows and divides in an uncontrolled way. It makes lots of cells that don’t die off in the way normal cells do. These cells eventually make up a tumour (lump). Or in a blood cancer (which is called leukaemia) there won’t be a tumour, but lots of abnormal cells will be produced.
Position of the bile duct
Diagram of cells forming a tumour
View a large version of the diagram of cells forming a tumour
Sometimes a tumour can turn out to be benign (which means it’s not a cancer). A tumour that is a cancer is sometimes called a malignant tumour.
Doctors can tell whether a tumour’s benign or malignant by removing a small piece of tissue (called a biopsy) and examining the cells under a microscope.
- In a benign tumour the cells don’t spread to other parts of the body. They usually only cause a problem if they grow too big and press on the tissue close by.
- A malignant tumour is made up of cancer cells. If they’re not treated, the cells can spread in the same area or to other parts of the body.
Video about blood cells Back to top
This animation shows how blood cells are made, how they function and some of the possible effects of cancer treatment on your blood.
Tell us what you think of our videos to help us improve what we do.
We don’t know what causes most cancers, especially the types that young people get. Doctors and scientists are researching this.
Remember that for most cancers:
- we don’t know the cause
- it isn’t anything you’ve done that’s caused it.
Risk factors are things that can increase the chances of developing some cancers. Here are some examples:
- Smoking can damage the DNA in our cells and can eventually lead to cancer.
- Having too much sun exposure, getting sunburnt and using sunbeds can damage skin cells. This can increase the chances of getting skin cancers like melanoma. Very rarely, cancer can be caused by a faulty gene that’s passed on through a family (inherited). But this doesn't often happen with the types of cancer young people usually get.
- It’s important to remember that you can’t catch cancer.
Different types of cancer Back to top
Cancer in teenagers and young adults is pretty rare. Most cancers are diagnosed in people over 65. Although there are over 200 different types of cancer, certain cancers are more likely to affect teenagers and young people. Some of these are:
If you’ve been told you have cancer, you’ll probably feel scared, shocked and not sure what it all means. Getting support from family, friends and the doctors and nurses looking after you can really help.
Finding out a bit more about the type of cancer you have can also help. Understanding it better might make seem it a bit less scary. And you can also learn some of the things you can do to help yourself.
Many cancers in teenagers and young people can be cured with treatment. The type of treatment you get depends on different things, such as the type of cancer, where it is and whether it’s spread to another part of the body.
The main treatments are:
- surgery - the removal of the cancer under anaesthetic
- chemotherapy - having anti-cancer drugs to destroy the cancer cells
- radiotherapy - high-energy x-ray treatment.
Other anti-cancer drugs can also be used. These are called targeted therapies (biological therapies or monoclonal antibodies).
Can cancer come back after it’s been treated? Back to top
Cells can sometimes spread from where the cancer started (the primary cancer) and go to other parts of the body. These cells can eventually make another cancer, which is called a secondary cancer or a metastasis.
Cells can spread in different ways:
- They can spread directly into tissue close by.
- They can travel in the blood.
- They can travel through the lymph nodes (sometimes called glands). The lymph nodes are part of the body’s immune system, which protects us from infection and other problems.
It’s common to have treatment to reduce the risk of the cancer spreading or coming back (called adjuvant treatment). For example, radiotherapy and chemotherapy are often given after surgery. This is to get rid of any cancer cells that might be left behind, or any that have spread to other parts of the body.