Adults can check their risk of developing potentially fatal melanoma skin cancer with a simple new questionnaire online.
The new self-assessment tool, run by an Australian research group, was set to go live overnight.
The tool can be accessed here
It is for people aged 40 or over and based on seven questions that will predict their risk of developing melanoma within 3.5 years in five categories from "very much below average" to "very much above average".
New Zealand has one of the highest rates of melanoma in the world.
Each year around 2400 new cases of melanoma are diagnosed and 350 people die from the disease.
It can usually be treated effectively by removal of the tumour if detected early, before cancer cells have started to spread. But the survival rate is much lower in so-called invasive or "malignant" melanoma.
The aim of the new tool is to prompt people at increased risk of melanoma to get suspicious-looking moles checked out sooner. And its developers urge everyone to be "sun smart" about exposure to the sun.
People whose melanoma prediction comes back as above average or higher are advised to talk to a doctor about whether they need a regular skin check.
"This online risk predictor will help identify those people with the highest likelihood of developing melanoma so that they and their doctors can decide how best to manage their risk," said one of the developers, Professor David Whiteman, of the Berghofer Queensland Medical Research Institute.
"Regular screening of those at highest risk may help to detect melanomas early, and hopefully before they've spread to the lower layers of the skin and other parts of the body.
"Importantly, in this study we found that people's actual risk of melanoma was quite different to their own assessment. This highlights the importance of getting personalised advice on your melanoma risk …"
The online tool is based on a study that followed more than 40,000 Queenslanders aged 40 to 69 for an average of 3.5 years to see how many developed melanoma and what their risk factors for the disease were.
These were narrowed down to seven statistically significant predictors of invasive melanoma: age, sex, ability of the skin to tan, number of moles at age 21, number of skin lesions treated, hair colour, and sunscreen use.
Whiteman said the tool was very accurate for people at lower risk of melanoma. It tended to inflate readings for some people at high risk.
"That means some people in the high risk category end up not getting melanoma …"
Some in New Zealand, while supportive of a new skin cancer-prediction aid, cautioned that the best advice for Kiwis was to keep an eye on their own and their loved ones' skin and to see a doctor.
Skin specialist Associate Professor Amanda Oakley expressed admiration for Whiteman's work, but said melanoma prediction tools were specific to their population and New Zealand had its own, produced by an Otago University researcher and used by GPs.
Skin cancer doctor Sharad Paul said the Queensland tool confirmed well-known risk factors.
He advised annual skin checks for adults with risk factors such as fair skin, history of childhood sunburn, an outdoor occupation, history of sun bed use and family history of skin cancer.
Cancer Society Auckland chief executive John Loof said, "Any tool that helps raise awareness around skin cancer is helpful. There are a number of self-diagnosis applications and websites.
"This new one, some of the inputs are subjective, for example tanning ability. There's potential for people to get that wrong. If that's the case, there's a danger that people could get a false sense of security - over-estimate the benefits of this [tool] and under-estimate some of the risks."
He said people should protect themselves from the sun with sunscreen, clothes, a hat, shade and sunglasses. They should check their skin and have suspicious lesions checked by a doctor.
"There's no substitute for an annual skin check as part of an annual health check. It might lead to more regular or specialist monitoring for some people."
Vanessa McSaveney was diagnosed with melanoma. She had two spots found on her back and one on the side of her neck.
Early detection of the tumours, following a spur-of-the-moment decision to get checked, means they are easily removed.
McSaveney told Herald Focus that she couldn't have relied on a self-check because she couldn't even see the melanoma on her neck.
Asked about her history of sun exposure, McSaveney said she probably had sunburn as a child. She used zinc cream on her nose and wore a hat but didn't use sunscreen.
The top five
The strongest predictors, in the online tool, of later invasive melanoma in Queenslanders were:
• Age. People over 65 had a 2.3 times higher risk of developing melanoma than those 40-45 or younger.
• Sex. Men's risk was 2.1 times higher than women's
• Tanning ability. Those whose skin doesn't tan had a 4.8 times higher risk than those whose skin tans deeply
• Number of moles at age 21. Those who had many had a 4.4 times higher risk than those who had none
• Number of previous skin lesions treated. Those who had 21 or more treated had a 2.5 times higher risk than those who had none treated