Scientists have developed a test which reliably predicts the spread or return of the most deadly form of skin cancer.
The Newcastle University team made the breakthrough in understanding how skin cancer tumours grow.
The test, known as AMBLor, is applied to a standard biopsy of the primary melanoma when it is removed.
Professor Penny Lovat, who led the work, said it will provide reassurance to patients who are diagnosed with an early stage melanoma.
"Our test offers a personalised prognosis as it more accurately predicts if your skin cancer is unlikely to spread," she said.
"This test will aid clinicians to identify genuinely low-risk patients diagnosed with an early stage melanoma and to reduce the number of follow-up appointments for those identified as low risk, saving the NHS time and money."
Currently, primary tumours are removed by surgery and pathologists study the biopsy under a microscope to determine the stage the skin cancer is at and the risk of it spreading.
Even if defined as low risk, the patient is followed up in a clinic for as long as five years.
'Like mortar crumbling away'
Prof Lovat said melanoma is the fifth most common cancer in the UK - with about 16,000 cases last year - and an increasingly worldwide problem.
"Incidence rates are set to increase by more than 60% by 2040, and 91% of patients are diagnosed with some early-stage melanoma," she told BBC Radio Newcastle.
The research, supported by The British Skin Foundation and carried out in association with the university spin-out firm Amlo Biosciences, has been published in the British Journal of Dermatology.
The foundation's chief operating officer, Phil Brady, said: "The development of the AMBLor test can alleviate stress and anxiety for patients caused by this potentially deadly skin cancer, whilst increasing efficiency and reducing costs to the NHS."
Researchers found that early stage melanomas which are at risk of spreading secrete a growth factor which causes the reduction, or downregulation, of certain proteins in the skin overlying the tumour.
"When these proteins are lost, gaps develop - like the mortar crumbling away in the wall," Prof Lovat explained.
"This allows the tumour to spread and ultimately ulcerate, which we know is a process associated with higher risk tumours.
"Our new understanding of this biological mechanism underpins the test we have available."
The team has made an application for the test to be available on the NHS.