Warnings that too much sunshine can lead to the most deadly form of skin cancer have been over-emphasised, a study has claimed.
It found that, although sunbathing is a risk factor, the number of moles on a person’s skin is the most important indicator of whether they will go on to develop melanoma.
The scientists also identified two genes that dictate how many moles someone will have, and their risk of getting skin cancer.
Research suggests that genes rather than sunshine are the main cause of the cancer
The research, published in the journal Nature Genetics, is likely to reopen the debate over whether official health warnings about avoiding the sun are overstated and too general.
The study’s authors said such warnings would be more useful if they focused on those most at risk – namely anyone with more than 100 moles on their body, redheads and people with fair skin – and taught them how to check their moles for changes in shape, size or colour.
Although melanoma accounts for just 10 per cent of skin cancer cases in the UK, it is responsible for the most deaths, killing 1,500 a year. More than 9,500 Britons are diagnosed with the condition annually.
Tim Spector, professor of genetic epidemiology at King’s College London, and one of the study’s authors, said: ‘The number of moles you have is one of the strongest risk factors for melanoma –stronger even than sunshine. This paper shows that we found two important genes that control the number of moles you have.
‘Those genes also give you an extra risk of melanoma.’
Dr Veronique Bataille, a dermatologist at West Hertfordshire NHS Trust, added: ‘You often read that nearly all melanomas are caused by sunshine, which is not supported by the evidence.
‘Let’s keep sunshine in the picture because it does make you age and causes you wrinkles. But let’s move away from scaring people by saying they are going to die because they go in the sun.’
Sara Hiom, of Cancer Research UK, said: ‘Everyone should be aware of changes in their moles and report anything worrying to their GP.’