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Mole number link to skin cancer

people with fair skin, freckles, red hair and moles most at risk. Increased risk in people with most moles

People with more moles on their skin are at a greatest risk from melanoma, the most dangerous form of skin cancer, new research has found.

Scientists at the University of Leeds, looked at over 300,000 different genetic variations in over 10,000 people to try and pinpoint the genes most significant in causing melanoma, responsible for over 2,000 deaths each year in the UK.

It's already known that people with fair skin, red hair and who sunburn easily are most at risk of developing melanoma, and conversely that those diagnosed with melanoma are more likely to be have red hair and freckles. This was confirmed by the study, but to a greater degree than anticipated.

However, the scientists also found a link between the number of moles on a person's skin and their risk of developing melanoma. And the risk was not associated with skin colour.

Overall, the study identified at least 5 genetic factors. A person having all 5 factors is around 8 times more likely to develop melanoma than those carrying none, although most people have at least one of the factors.

Interestingly, extended exposure to sunlight is not enough in itself to cause the disease, as Professor Tim Bishop of the University of Leeds, one of the leaders of the study, explained:

"If you take the people who have the greatest exposure to sunlight – those who work outside for example – and compare them to those with the least exposure, their risks of getting skin cancer are actually quite similar. Statistically, the differences are quite negligible."

"What we do know is that the combination of particular genes and a lifestyle of significant sun exposure is putting people at greatest risk," he added.

Sara Hiom, Cancer Research UK's director of health information, said: "The more we can understand malignant melanoma through research like this the closer we should get to controlling what is an often fatal cancer.

This study confirms Cancer Research UK's advice in its SunSmart campaign that people with lots of moles – as well as those with red hair and fair skin – are more at risk of the most dangerous form of skin cancer and should take extra care in the sun.

Around 48,000 people worldwide die of melanoma each year. It is more common in males and those with pale skin – and is on the increase. It is widely believed that the increase in melanomas is largely due to social and behavioural activities, such as increased exposure to the sun, partly caused by the availability of cheaper foreign holidays. Sunny holidays increase the risk because it is intermittent sun exposure which causes melanoma rather than daily exposure over longer periods of time.

Further information

University of Leeds Information
Cancer UK SunSmart web site

This article was published on Tue 7 July 2009

Image © slocummedia -

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