Smartphone apps that claim to detect skin cancer could delay proper medical diagnosis and potentially life-saving treatment, US expert have warned.

Apps that analyse photographs of the skin to detect possible melanoma skin cancer often give inaccurate results, according to scientists from the University of Pittsburgh School of Medicine.

Researchers used four apps to analyse 188 images of skin lesions. Three of the apps incorrectly classified 30 per cent or more melanomas as 'unconcerning'.

"These tools may help patients be more mindful about their health care and improve communication between themselves and their physicians," said Dr Laura Ferris, one of the researchers.

"But it's important that users don't allow their 'apps' to take the place of medical advice and physician diagnosis."

Every year around 12,800 people in the UK are diagnosed with melanoma, the most serious form of skin cancer. And around 2,200 die from the disease.

The study concentrated on apps that are available on the two most popular smartphone operating systems.

Each of the apps is designed to analyse digital images taken with the phone to advise the user whether their moles are potential melanomas or if they are likely to be benign.

The apps work in different ways. Some returned results based on automated algorithms, whereas one sent images to a skin specialist.

All of the apps featured disclaimers stating they were for educational purposes only, but researchers said there was a risk that patients might rely too heavily on the verdict generated by the phone.

"If they see a concerning lesion but the smartphone app incorrectly judges it to be benign, they may not follow up with a physician," said Dr Ferris.

"Technologies that decrease the mortality rate by improving self- and early-detection of melanomas would be a welcome addition to dermatology. But we have to make sure patients aren't being harmed by tools that deliver inaccurate results."

Dr Claire Knight, health information manager at Cancer Research UK said the finding was worrying.

"Using a mobile phone app may seem like a convenient alternative to visiting the doctor about any changes to your skin, but if the app gets it wrong a potentially deadly skin cancer could be missed," she said.

"If you notice any changes in the size, shape or colour of a mole or any other change to a mole or normal patch of skin, consult your doctor, not your phone."

Source: CRUK