What is cancer and how does it start - transcript

Voiceover - What is cancer and how does it start?
Cancer begins in our cells

Our bodies are made up of billions of cells

The cells are so small the only way to see them is under a microscope

Different types of cells do different jobs

So for example, our skin cells are different to the cells found in our stomach, and they are different to the cells in our bones.  But they all have a similar basic structure. 

Our cells are constantly dividing, dying and being replaced. This normally happens in a controlled way to make sure we have the right number of each type of cell in our body.

Cancer happens when something goes wrong when cells are dividing.

The damaged cell might start to grow and multiply too much and form a tumour.
This can happen anywhere in the body.

For a cancer to start, changes happen in the cell’s nucleus. This is its control centre. The nucleus contains DNA. Sections of DNA are called genes. This is where the changes happen.

Let’s explain, the genes are like the cell’s instruction manual.

Gene changes might be like a page missing from the manual.

So it could be that there is a missing gene or it might be that there are too many copies of a gene.

Or the genes are not in the right order.

This means that the cell doesn’t know when to stop and start dividing and where in the body it should live and a tumour can develop.

If this continues it can grow into nearby tissues and spread to other parts of the body.

Blood cancers are a little different. 

For example leukaemia is a cancer of the white blood cells. 

Too many faulty white blood cells are made and build up in the blood stream.

So, what causes the changes in the cell DNA? They could happen by chance when any cell is dividing.

But outside factors such as tobacco smoke, alcohol or sun exposure can make mistakes more likely. 

Much more rarely people can inherit gene changes that make them more likely to develop cancer.

For more information about cancer go to C R U K dot org forward slash about hyphen cancer.