Causes and risk factors of melanoma

The main risk factor for developing melanoma is exposure to ultraviolet light (UV light). This can be through sunlight or sunbeds.

What are risk factors?

The causes of melanoma are not fully understood. There are certain things that can increase the risk of developing melanoma. These are called risk factors. Having a risk factor does not mean you will get cancer. And not having a risk factor does not mean that you will not get it.

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The main risk factor for developing melanoma is older age. More than a quarter of melanomas diagnosed are in people over the age of 75. But melanoma is also more common in younger people than some other types of cancer.

Ultraviolet light exposure (UV exposure)

The other main risk factor for developing melanoma is exposure to UV radiation. This can be through natural sunlight or the artificial light used in sunbeds or sunlamps. UV radiation damages the DNA (genetic material) in our skin cells. This can cause skin cancer such as melanoma.



In the UK, the number of white people developing melanoma and other skin cancers is rising. One of the reasons for this is more sun exposure. Public awareness has also led to a rise in the number of early melanomas being diagnosed.

It is important to protect yourself from too much sun. You should not stay out in the sun for long enough to let your skin redden or burn. Skin that is sunburned is usually red, sore and warm to touch. It may feel like this for up to a week.

But national guidelines say getting a small amount of sunshine on a regular basis helps our bodies make vitamin D. This keeps our bones and teeth healthy. It also helps our immune system and has some anti-cancer effects.

The amount of sun exposure you need depends on:

  • your hair and skin type
  • the time of year
  • which part of the world you live in.

Severe sunburn that causes the skin to blister, especially during childhood, can increase the risk of melanoma in the future.



Sunbeds use artificial UV rays that damage the DNA in your skin. They may increase the risk of melanoma. Your risk is higher the more you use a sunbed or lamp, and the earlier in life you start using them.

It is important not to use sunbeds and to protect yourself from too much sun. This is especially important if you have had melanoma or any other type of skin cancer in the past. It is also important if you have an increased risk of melanoma.

Your skin type

You will be more sensitive to the sun if you have:

  • fair skin
  • red or blonde hair
  • green or blue eyes
  • freckles.

This skin type will burn more easily. This means people with this skin type are more at risk of getting melanoma. Having naturally darker skin lowers your risk of getting melanoma. But it does not mean that you will never get it. People of Indian, Asian and African descent have a lower risk of melanoma because their skin produces more melanin.

Having lots of moles and unusual moles

People who have a lot of moles, especially those with over 100 moles, have a higher risk of getting melanoma. People with moles that are bigger than average, or that have an irregular shape or colour are also at higher risk. These types of moles rarely change into melanoma, but it is important to check them regularly for changes. Having lots of moles or irregular moles can run in some families.

Your risk of melanoma is also increased if:

  • you were born with a dark, hairy mole
  • you were born with a large birth mark (over 20cm)

The risk from average size birth marks is very small.

If you have lots of moles or unusual moles, you can be referred to a skin specialist for advice and an assessment of your skin.

Family history of melanoma

Your risk of developing melanoma increases if you have a close relative who has had melanoma. This may be because you have similar skin colour. But it could also be because about 1 in 10 melanomas (10%) are thought to be caused by genes that can run in families.

If you have a strong family history of melanoma, you may be referred to a genetic counsellor to discuss having a genetic test. The test will look for a gene called p16. This is a gene that can increase the risk of melanoma. The p16 gene may also be linked to an increased risk of pancreatic cancer. Your genetic counsellor will talk to you about this. Like all cancers, melanoma may also be caused by a large number of genes that we cannot test for yet.

People with a very strong family history of melanoma and other types of cancer should be referred to a specialist. Your GP can refer you to a dermatologist and a family cancer clinic. We have more information on cancer genetics.

Reduced immunity

People with a weakened immune system have an increased risk of melanoma. This could be because of HIV or because they are taking drugs that suppress the immune system. For example, drugs to suppress the immune system after an organ transplant.