Don't rely on apps for melanoma checks: expert

The app uses an algorithm to assess if uploaded pictures show signs of melanoma through a "risk classification". Photo / Thinkstock

A world-leading melanoma expert is warning Kiwis not to rely on a raft of new smartphone apps that claim to detect the potentially deadly skin cancer.

Dozens of apps have cropped up in recent years claiming to be able to monitor and identify signs of skin cancer.

One of the most recent, SkinVision, says on its website that users can upload images of moles on their skin and a mathematical algorithm then analyses the picture and provides a "risk classification".

It then tells users whether any abnormal or dangerous characteristics have been detected.

Although it warns that the app is not diagnostic, it says it has a 70 per cent accuracy rate.

Dermatologist Dr Amanda Oakley, an honorary associate professor at the University of Auckland, said the concern was that people may be told that their lesion was all right when it was not.

"Most of them are very responsible and say, 'Don't rely on this'," she said.

"But our greatest fear is that a melanoma could be missed."

The cameras on smartphones could not come close to the equipment used by dermatologists, who had dermoscopy equipment that magnified lesions many times, allowing them to see the skin's sub-structures.

The apps could also conclude that harmless lesions were melanoma when they were not.

Melanomas are rarer in young people with 92 per cent occurring in people aged over 40 but, Oakley said, "the older you are the less likely you are to use an app".

Other risk factors for melanoma include having lots of moles, and if you've had one before.

"The apps are fabulous because they provide people with further information.

"But they shouldn't be relied upon."

Cancer Society skin cancer adviser Louise Sandford said New Zealand had the highest rates of melanoma in the world. More than 2,000 new cases are diagnosed each year and 300 people a year die from the condition.

New Zealand had UV levels 40 per cent higher than at corresponding latitudes in the Northern Hemisphere.