Skin cancers can’t be safely ruled out with a visual exam alone, review warns

Around one in 10 melanomas would be missed with sight checks and they should not be relied on alone, review authors say

Visually inspecting a mole is not enough to safely rule out skin cancer according to a review which calls for more technological assistance to guide GPs’ initial assessments.

Researchers said around one in ten melanomas would be missed with just a visual inspection at the doctor’s, following a review of evidence from the most well conducted trials on the subject which was led by the University of Birmingham.

Visual inspection alone was also unreliable when done by a specialist dermatologist, the review found, however virtually all specialists would use a magnifying device – a dermoscope – for their assessment and this improved diagnoses.

“Error rates from visual inspection are too high for it to be relied upon alone … other technologies need to be used to ensure accurate diagnosis of skin cancer,” the report said.

However researchers stressed that in a real world setting most patients would be referred where there was uncertainty, or patients would be given instructions by their GP to keep moles under inspection.

The success rates of different assessment methods were assessed as part of a Cochrane review, a gold-standard appraisal of medical evidence to date.

“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,” lead author Dr Jac Dinnes told The Independent, although most of the research was done in a specialist setting.

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

“But that’s just one check, and when we talk about primary care people are going to go back if they have concerns or things are changing.”

The review is significant given the rising rates of skin cancer worldwide. In the UK there are around 16,000 new cases every year, a figure that has increased 128 per cent since the 1990s according to Cancer Research UK.

The Cochrane review looked at an array of diagnostic methods for skin cancers to see how new technology can improve diagnoses.

The study said GP diagnosis of skin cancers could be improved by making greater use of dermoscopes and by sending images to dermatologists for assessment to prevent excessive referrals swamping services.

The review also tested whether publicly available apps enabling people to take a picture of their melanoma and have it analysed were deemed to significantly underestimate risks.

Advanced systems using machine learning algorithms which were trained on a library of thousands of dermoscope images of moles to assist diagnosis identified more cancers than doctors.

However, such systems “also produce far more false positive diagnoses than dermoscopy and could lead to considerable increases in unnecessary surgery”, which could create more costs for the NHS.

“Early and accurate detection of all skin cancer types is essential to manage the disease and to improve survival rates in melanoma, especially given the rate of skin cancer worldwide is rising,” Dr Dinnes added.

“We have found that careful consideration should be given of the technologies that could be used to make sure that skin cancers are not missed, at the same time ensuring that inappropriate referrals for specialist assessment and inappropriate excision of benign skin lesions are kept to a minimum.”