Highlights
- Excessive exposure to ultraviolet (UV) radiation from the sun can cause DNA damage to the skin cells.
- For people with darker skin tones, their risk factor is lower, but they can still get skin cancer.
- People with dark skin are more at risk of vitamin D deficiency.
Why does Australia have one of the highest skin cancer rates in the world?
According to the Australian Bureau of Statistics, of the Australians living with cancer in 2017-18, nearly one in three (30.8 per cent) had skin cancer, making this the most common type of cancer in the country.
Professor David Whiteman, Group Leader at the Cancer Control Group, QIMR Berghofer Medical Research Institute, says it’s due to a combination of factors, including geography and migration.
“In the Southern Hemisphere, our country is located at fairly low latitudes, so the amount of sunlight that hits the ground in Australia is much higher than in Europe and Northern Asia and other parts of the world, like North America. So there is a lot of UV radiation striking the earth’s surface where we live," he says.
It’s also about the way Earth orbits the Sun.
Source: Getty Images/maps4media
"in our summertime in Australia, the actual intensity of the sun’s rays are stronger because we are a bit closer to the sun than the equivalent time in the Northern hemisphere for their Summer," explains Prof Whiteman.
He says because most Australians are of European ancestry and mostly have fair skin, it is not suitable for Australia's environment with strong solar radiation.
Source: Getty Images/MB Photography
How does sun exposure cause cancer?
Excessive exposure to ultraviolet (UV) radiation from the sun can cause DNA damage to the skin cells. When this damage builds up, it can cause cancer.
"What happens is when the ultraviolet radiation hits the skin, it starts to change the DNA of the most superficial cells," says Sydney GP Ahmad Hasanien, who is also accredited in skin cancer.
"Day after day, year after year, the cancer cells start to evolve — whether it be the milder cancer, the basis for cancer, to the intermediate and potentially life-threatening cancers or life-threatening melanomas.”
If the body’s internal DNA repair mechanism does not repair this damage, faulty cell replication can occur, triggering cells' abnormal growth, which eventually becomes cancers.
Dr Hasanien says the UV Index on a typical summer day in Australia is so high that unprotected sun exposure could mean a high risk of harm.
“On a typical day, a UV index of 12 of Sun in Australia, I would probably avoid going out, I would probably avoid taking my kids out," he says.
On a sunny winter day, the UV index would be three or four, which Dr Hasanien says is mild to moderate, and the duration of the UV radiation is short.
"But in summer, for the period between 8 am and 4.30 pm, it’s almost always reaching a level between 12 and 14," he adds.
Source: Getty Images/Stuart Westmoreland
'Slip, slop, slap, seek, slide.'
Paige Preston is the former Chair of the Skin Cancer Committee at the Cancer Council of Australia.
She encourages all Australians to check the UV levels for their specific location before heading outside — using the or checking the Bureau of Meteorology’s website.
"We recommend that all Australians use multiple forms of sun protection when the UV level is three or above," says Preston.
"When the UV level is 3 and above to use a slip-on protective clothing that covers as much skin as possible, slop on some sunscreen, which is 30 SPF or higher or a spectrum and water-resistant, slopping on a hat that covers face, neck and ears, seeking shade and sliding on sunglasses."
Source: Getty Images/Elizabeth Fernandez
Are people with darker skin tones less at risk of developing skin cancer?
For people with dark skin, their risk factor is lower, says Mr Whiteman, but this does not mean that they are not at risk at all.
He says melanin offers protection against DNA damage due to UV radiation.
"It puts a little barrier around the nucleus of the skin cells, like a shield and absorbs all that UV radiation and it’s very protective, and it stops the damage of the DNA in those cells," he explains.
But Dr Hasanien says he sees many dark-skinned patients with skin cancer at his practice.
"Everyone is different. In medicine, a good doctor will tell his patient, ’There is a risk factor. Please avoid the risk factor’.
"The ultraviolet radiation is a risk for skin cancer and a dark person, light-coloured person, they are exposed to the same risk factor," he says. "A dark person has the protection but it does not mean that you are always protected. Anyone can get skin cancer even if you are dark and I have this in my practice."
Vitamin D deficiency
But not going out in the sun may mean vitamin D deficiency, especially for people with darker skin types.
Cancer Council’s Paige Preston says such people should speak to their GP about vitamin D supplements rather than exposing themselves to the sun for extended periods.
“There are some groups that are at risk of vitamin D deficiency, so these are people who have more melanin and darker skin tones, people who cover their skins for religious or cultural reasons, and also the elderly," she says.
Getting a tan
Mr Whiteman cautions people against trying to get a tan this summer, believing that it would protect them against damage from the sun. He says tanning causes significant damage to the skin and the DNA.
A crowded Bondi Beach, in NSW, on a Summer day. Source: Getty Images/Matteo Colombo
A tan is a shock to the system.
"The reason our skin tans is almost like a rescue response because we only start to tan after we sustained damage to our skin cells," he says.
"It’s like shutting the gate after the horse has bolted. It means that the damage has already occurred, and the skin tries to stop any more damage from occurring."
Ms Whitman says once a person has a tan, it does provide sun protection — that’s what it has evolved to do.
"But for people who try to get a tan, the only way they can acquire a tan is by causing damage to their skin and to their DNA."
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