An Australian melanoma expert says although some people have a genetic susceptibility to developing melanoma, exposure to the sun’s ultra violet (UV) rays poses a far greater risk.
Professor David Whiteman has told the national Melanoma Summit in Auckland that the genetic contribution to melanoma is pretty well understood.
“In the past, we’ve been able to recognise people with genes that put them at higher risk just by looking at them, such as those with fair skin, red hair, freckles and lots of moles.
“Now we’re finding other genes that are melanoma-specific. Each might carry a low risk, but when you add them all together across the genome, they can double or even triple your risk of developing a melanoma.
“But regardless of genetic susceptibility, the finger of blame is still pointed squarely at exposure to the sun’s UV being the main cause of melanoma and therefore sun protection is still the best form of prevention.”
Professor Whiteman says even allowing for genetic factors, everyone with fair skin living in New Zealand is at high risk for melanoma – at least four times that of people who live in the UK or Europe to where most trace their ancestry.
“There’s very strong evolutionary selection in favour of darker skin in a sunny climate. Māori and Pacific people who have darker skin have a much lower genetic risk of developing melanoma because the melanin pigment in their skin is a very effective shield for UV radiation.”
He says there’s also a lot of evidence that melanomas are the most “deranged” of tumours in terms of the number of mutations they have and that those mutations are characteristically UV-induced.
“Fair skinned people who live in New Zealand who don’t develop melanoma are very fortunate because they clearly have some kind of ability to repair the sun’s damage.
“The bottom line is that the sun is potentially lethal for certain melanomas and everybody – particularly those with fair skin – needs to protect themselves from the sun.”
The risk of developing melanoma is strongly related to a history of one or more sunburns in childhood or adolescence.
“We therefore have a responsibility as a society to minimise sun exposure for those who can’t protect themselves. For example, we need to make sure school children aren’t playing cricket or having swimming sports in the middle of a hot summer’s day.”
Professor David Whiteman is Head of the Cancer Control Laboratory, Coordinator of the Population Health Department and Coordinator of the Melanoma and Skin Cancer Research Centre at the QIMR Berghofer Medical Research Institute in Brisbane. His work follows the parallel paths of discovering how environmental and genetic factors interact to cause cancer, and then applying this knowledge to the prevention and control of disease. Professor Whiteman’s visit to New Zealand has been made possible by the Cancer Society of New Zealand.
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