Melanoma risks and causes
This page is about the risks and causes of melanoma skin cancer. There is information below on
Melanoma risks and causes
Melanoma is one of the 10 commonest cancers in the UK. More women than men get melanoma.
There is one main factor that increases the risk of developing melanoma - ultraviolet light. Ultraviolet light comes from the sun or sunbeds. But some people are more at risk of getting melanoma than others. Risk factors related to sun exposure include
- Moles - the more moles you have, the higher your risk
- Being very fair skinned - especially with fair or red hair, or having lots of freckles (although people with darker skins can still get melanoma)
- Sunburn - getting badly sunburned increases your risk of melanoma, particularly in childhood
- Where you were born - fair skinned people born in a hot country, such as Australia or Israel, have a higher risk of melanoma throughout their life
- Sun exposure - on holiday, as well as sitting in the sun or sunbathing at home
- Sunbeds – using sunbeds, particularly before the age of 35
- Sunscreen - using sunscreens may protect you, as long as you also limit sun exposure. Don't think that using sunscreen allows you to spend as long as you like in the sun.
There are a couple of other known risk factors. You are more at risk if a close relative has had melanoma. Having had a melanoma or another type of skin cancer increases your risk. Having a lowered immunity increases your risk of melanoma, as it does with a number of cancers.
In the UK each year, more than 10,400 people are diagnosed with melanoma. More women than men get melanoma in the UK. It is the 6th most common cancer overall in the UK, excluding non melanoma skin cancer. The number of people getting melanoma now is 4 times higher than in the 1970s. It is a rare illness in the under 14's. But in people over 15, the incidence steadily rises with age. The highest incidence is in people over 80.
There is one main factor that increases the risk of developing melanoma - ultraviolet light (radiation). Ultraviolet light comes from the sun or sunbeds. But some people are more at risk of getting melanoma than others, as the rest of this page explains.
Who gets melanoma
In the UK each year, more than 8,900 people are diagnosed with melanoma. More women than men get melanoma in the UK. It is the 7th most common cancer overall. It is the 6th commonest cancer in women and the 10th most common in men. The number of people getting melanoma now is 4 times higher than in the 1970s. It is a rare illness in the under 14's. But in people over 15, the incidence steadily rises with age. The highest incidence is in people over 80.
Some of us have more moles than others. The more moles you have on your body, the higher your risk of melanoma. Of course this doesn't mean you will definitely get melanoma if you have lots of moles. But it does mean you should be very careful about exposing yourself to the sun. And you should keep an eye on all your moles. There is more about this in the page on symptoms of melanoma. People who have lots of abnormal moles (dysplastic naevus syndrome) have a slightly higher risk of melanoma than the general population. Also, people with just one unusually shaped or very large moles (atypical naevi) have an 60% increased risk of melanoma. The risk increases with the number of atypical naevi, and people with five or more have 10 times the risk of people without any atypical naevi.
People who are very fair skinned, especially with fair or red hair, are more at risk of developing melanoma. So are people with a lot of freckles. People with darker skins can still get melanoma but they have more natural protection against it. It is relatively rare for black people in the UK to get melanoma. If melanoma occurs in African or Asian people they are mostly a type that occur on the feet (acral lentiginous melanoma). In the UK, if you are fair skinned and have a tendency to freckle in the sun, you are most at risk.
If you have a tendency to get sunburn, you are at more than average risk of melanoma. People most at risk are those who don't tan at all, such as the fairest skinned people and people who go red and then peel before getting a tan.
Research has looked into the link between sunburn and melanoma. Sunburn definitely increases the risk of melanoma. People with melanoma are twice as likely as other people to have been badly sunburned at least once in their lives. The risk is higher if you have had sunburn several times in your life. Sunburn in childhood is even more damaging than sunburn as an adult.
Fair skinned people born in a hot country, such as Australia or Israel, have an increased risk of melanoma throughout their life. Their risk is higher than people who went to live in a hot country as a teenager or people with similar skin colouring who live in cooler climates. Fair skinned people born in a hot country may have exposure to the sun as a baby and young child - when the skin is most delicate. This doesn't mean you will definitely get melanoma, of course. It just means you should be aware of taking care of your skin in the sun.
In the UK, most of us are not exposed to the sun for the whole year. But over the past couple of decades, more and more of us have been going abroad for two or three weeks a year for a holiday and to get a good tan. This concentrated sun exposure is more of a risk for melanoma than being in the sun for part of the day throughout the year. In fact, a worldwide analysis of studies shows that people who work outdoors and so are in the sun much of the time are less at risk of melanoma than people who work indoors and take part in outdoor hobbies.
The number of people getting melanoma has shot up in the UK since it became popular to have a tan and go abroad for holidays. But you don't have to go abroad. We do occasionally have hot spells in the UK. In one study in Scotland, a third of melanoma patients had never been abroad but they had sunbathed at home.
People with higher socioeconomic status have a higher risk of melanoma and this is probably due to well off people taking more foreign holidays.
Makers of sunbeds will keep trying to tell you that their type of sunbed is safe. But they aren't. Sunbeds haven't been around for long enough for us to prove beyond all doubt that they cause as much malignant melanoma as lying in the sun. But laboratory research has proved that the type of ultraviolet light used in sunbeds (UVA) can cause all types of skin cancer. More studies are showing that using sunbeds definitely increases the risk of melanoma. In 2007, an analysis of 23 studies reported that people have an increase in risk if they have ever used a sunbed. And the risk was highest for people who had used a sunbed before the age of 35.
The ultraviolet light in the sun is made up of two different wavelengths of light. These are called ultraviolet A and B (UVA and UVB). In the mid 1980s, sunbeds that only gave off UVA were developed. We know that it is the UVB in the sun that causes burning. So the manufacturers said that UVA alone must be safe because it didn't burn you. This isn't true.
Using a sunbed to get a tan before you go on holiday can also increase the risk of melanoma. There is no such thing as a safe tan. For more information, see our section on preventing melanoma.
Many research studies have shown that using sunscreen does not reduce the risk of getting melanoma. It may even increase the risk. This may be because people wearing sunscreen stay longer in the sun because they think they are protected and so they actually get more exposure to ultraviolet light overall.
But a study in 2005 in Canada showed that using sunscreen may help to reduce melanoma risk. The study looked at 2 groups of school children over three years. One group was given a supply of sunscreen and parents were advised to apply it when their child would be spending more than 30 minutes in the sun. The other group did not get the advice or sunscreen. The group using sunscreen developed fewer moles. So sunscreen may help, because having more moles is known to increase melanoma risk. Sunscreens now are also more effective than those used 10 to 20 years ago. So using sunscreens, along with limiting exposure to the sun, may protect against melanoma in the future.
But it is important not to think that using sunscreen allows you to spend a long time in the sun. You still have to be careful. Most people don't put enough sunscreen on. There is more about using sunscreen in the section of CancerHelp UK on preventing melanoma.
If you have a close relative who has had melanoma, you are more at risk yourself. This is probably partly because we tend to share the same sort of colouring and skin type as our close relatives. Even if you have darker skin colouring, you should be careful in the sun, as you still have a slight increase in the risk of developing melanoma.
Some families tend to have large numbers of moles, or moles that are unusual (doctors call them 'atypical'). This used to be called 'familial dysplastic naevus syndrome', but this term isn't used much any more. The 'atypical' moles tend to be an irregular shape or colour. They also have a tendency to become cancerous (malignant). People with moles like this have a higher than average risk of melanoma. The highest risk factor known for melanoma is to have a very close relative (mother, father, brother or sister) with melanoma and to have abnormal looking moles yourself.
Scientists think that around 1 in 10 cases of melanoma (10%) may be linked to inherited faulty genes. Two of these genes have been identified and Cancer Research UK researchers are very close to identifying a third. For the small number of families who carry these genes, sun protection is even more important. People who have had melanoma and have a parent who has had melanoma have a risk of getting another melanoma that is 30 times higher than the general population.
People who have had a melanoma have a risk of getting a second melanoma that is 9 times higher than other people in the population. Studies have also shown that people who have had a non melanoma skin cancer have roughly double the risk of melanoma of the general population.
Because more women than men get melanoma, researchers have been very interested in whether hormones had a part to play. There has been a lot of research into this area, looking at
- The role of female sex hormones
- The pill and hormone replacement therapy (HRT)
- Pregnancy
There is no conclusive evidence that risk of melanoma is affected by any of these factors. Some women have a natural darkening of the skin during pregnancy. This may make moles show up more clearly. But it is not true that moles are more likely to become cancerous during pregnancy. There is also no evidence that pregnant women diagnosed with melanoma do worse than non pregnant women. If you are worried about this, talk to your GP.
A recent study showed that women who have had particular changes in their womb (endometriosis or fibroma) have a 30 to 60% increased risk of melanoma. However, other studies have not shown an increased risk so we need more research to know whether there is a link.
Studies have shown that people with reduced immunity are more likely to develop melanoma. People may have reduced immunity due to infection with HIV or AIDS or medicines given to suppress the immune system after an organ transplant.
One study has shown a higher risk of melanoma in people working as pesticide applicators who are exposed to an insecticide called carbaryl. The risk of melanoma increased further with more than 10 days of use per year and more than 10 years of use. However, more evidence is needed to support this early finding, and to rule out a role of other factors such as sun exposure patterns.
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