The naked eye is NOT strong enough to diagnose skin cancer

Doctors are missing thousands of cancerous moles because the naked eye is not strong enough to diagnose skin cancer

  • Review of 104 studies in research led by the University of Birmingham
  • Doctors should make greater use of magnifying devices when diagnosing
  • Medics should also send images to a more senior specialist if unsure  
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Doctors may be missing hundreds of cancerous moles because visually examining them is not enough to rule out skin cancer, research suggests.

A review of 104 studies has revealed around one in ten of the most deadly skin cancers are missed – even when ‘eyeballed’ by specialist dermatologists. 

Instead, doctors should make greater use of magnifying devices when making a diagnosis and send images off to a more senior specialist if they are unsure, the researchers stress. 

‘Error rates from visual inspection are too high for it to be relied upon alone,’ the Birmingham University scientists wrote. 

‘Other technologies need to be used to ensure accurate diagnosis of skin cancer.’

Visually examining a mole is not enough to rule out skin cancer, research suggests (stock)

The review was led by Dr Jac Dinnes.  

Melanoma is responsible for 75 per cent of all skin cancer deaths because of its ability to spread via the bloodstream or lymphatic system. 

Overexposure to UV light from the sun or sunbeds is the main cause.

Around 15,900 new cases occur every year in the UK, with 2,285 Britons dying from the disease in 2016, according to Cancer Research UK statistics. 

In the US, an estimated 178,560 cases will be diagnosed by the end of this year, with one person dying from melanoma every hour, Skin Cancer Foundation figures show.

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Diagnosis usually starts by examining the skin, with doctors looking for moles that are uneven, dark or have more than two colours, crusty, flaky, bleeding, large or raised.

As with all cancers, early diagnosis boosts the likelihood a patient will survive. 

Spotting the disease in stage one – when it has not spread – means almost 100 per cent of patients survive at least five years post-diagnosis.

But diagnosis at stage four – when it is advanced and may be in the lungs, brain or bones – means just 10 per cent of men and 25 per cent of women survive five years or more.  

The accuracy of different methods of assessing moles was analysed as part of a Cochrane review, which combines high-quality studies to create gold-standard healthcare decisions. 

‘Of the studies that were very clearly conducted in primary care for visual inspection, we found the chances of missing a melanoma were about one in ten,’ Dr Dinnes told The Independent.

‘It certainly was significant that just visual inspection with the naked eye alone was not fully reliable.’ 

Although visually inspecting moles can lead to inaccuracies, the review added that most checks are carried out by specialists rather than GPs. 

And specialists often use a magnifying device, known as a dermoscope, which boosts diagnosis accuracy. 

‘When used by specialists, dermoscopy is better at diagnosing melanoma compared to inspection of a suspicious skin lesion using the naked eye alone,’ the authors wrote.

They also stressed that patients tend to be referred on to a more senior specialist if there is any uncertainty. 

Dr Dinnes also said patients often go back for a second opinion if they have nagging concerns or their mole has changed.

Nevertheless, the review called for greater use of technology to improve diagnoses and prevent unnecessary referrals that overwhelm specialists. 

In a second review, the researchers tested the effectiveness of five diagnosis apps by uploading 332 pictures of suspicious moles, of which 86 were cancerous.

Results suggested accuracy at identifying known melanomas ranged from just seven per cent to 73 per cent, while reliability at dismissing non-serious cases ranged from 37 per cent to 94 per cent.  

Misdiagnosing melanoma can ’cause anxiety and lead to unnecessary surgery’, the authors wrote.

‘Smartphone applications using artificial intelligence‐based analysis have not yet demonstrated sufficient promise in terms of accuracy, and they are associated with a high likelihood of missing melanomas.’ 

This review only looked at two studies, carried out in the US and Germany, which included images taken by dermatologists, not patients. 

The scientists therefore stress the true accuracy of at-home apps is unclear. 


Melanoma is the most dangerous form of skin cancer. It happens after the DNA in skin cells is damaged (typically due to harmful UV rays) and then not repaired so it triggers mutations that can form malignant tumors. 

The American Cancer Society estimates that more than 91,000 people will be diagnosed with melanoma in the US in 2018 and more than 9,000 are expected to die from it.

Around 15,900 new cases occur every year in the UK, with 2,285 Britons dying from the disease in 2016, according to Cancer Research UK statistics. 


  • Sun exposure: UV and UVB rays from the sun and tanning beds are harmful to the skin
  • Moles: The more moles you have, the greater the risk for getting melanoma 
  • Skin type: Fairer skin has a higher risk for getting melanoma
  • Hair color: Red heads are more at risk than others
  • Personal history: If you’ve had melanoma once, then you are more likely to get it again
  • Family history: If previous relatives have been diagnosed, then that increases your risk


  • Removal of the melanoma:

This can be done by removing the entire section of the tumor or by the surgeon removing the skin layer by layer. When a surgeon removes it layer by layer, this helps them figure out exactly where the cancer stops so they don’t have to remove more skin than is necessary. 

  • Skin grafting: 

The patient can decide to use a skin graft if the surgery has left behind discoloration or an indent. 

  • Immunotherapy, radiation treatment or chemotherapy: 

This is needed if the cancer reaches stage III or IV. That means that the cancerous cells have spread to the lymph nodes or other organs in the body. 


  • Use sunscreen and do not burn
  • Avoid tanning outside and in beds 
  • Apply sunscreen 30 minutes before going outside
  • Keep newborns out of the sun
  • Examine your skin every month
  • See your physician every year for a skin exam 

 Source: Skin Cancer Foundation and American Cancer Society

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