Cancer starts in cells in our body.

Cells are tiny building blocks that make up the organs and tissues of our bodies. They divide in a controlled way to make new cells. This is how our bodies grow,

heal and repair.

Cells receive signals from the body telling them when to divide and grow, and when to stop growing.

When a cell is no longer needed or can’t be repaired, it gets a signal to stop

working and die.

Cancer develops when the normal workings of a cell go wrong and the cell becomes abnormal.

The abnormal cell keeps dividing, making more and more abnormal cells. These eventually form a lump (tumour).

Image Credit: Macmillan Cancer Support

The type of cancer you have depends on where it develops in the body, and skin cancers develop when cells within the skin become damaged and abnormal.


This is usually due to damage from ultraviolet radiation (UV) from the sun or sunbeds, which deliver very concentrated ultraviolet light.


We are all exposed to UV light and our bodies will usually repair the damage this causes automatically. If the exposure and damage is intense or prolonged however this makes it more difficult for our bodies to repair and this is when skin cancers may develop

Whether or not you will develop a skin cancer depends on many factors, see who’s at risk.

There are many types of skin cancer and they are named according to which cells are affected. They vary in how they look, how they behave and how likely (if it all) they are to spread to other parts of the body. For more information see “Types of skin cancer”

When skin cancers develop, the symptoms we see are lumps, spots or changes to our normal skin. The earlier we spot them, the easier they are to remove or treat, which is why it is helpful to check your skin regularly for early signs.

You can see how to do this and what to look for here.

Some types of skin cancer can spread by travelling to other parts of the body through the blood or lymphatic system, but it takes time for them to grow deep enough in the skin to reach these systems.


Most skin cancers are spotted, treated, and cured before this happens but this is another, very important, reason to check your skin regularly for early signs of skin cancer and see your doctor straight away if you are concerned.