UK researchers have found a way to test blood for circulating tumour DNA by looking at two genes associated with malignant melanoma, one of the deadliest forms of skin cancer.
Harmful mutations in the genes, BRAF and NRAS, occur in 70 per cent of malignant melanoma cases and the study found patients whose blood tested positive for these genes were much more likely to see the cancer return within a year of surgery.
Five years after surgery, a third of patients who had the faults were alive compared with 65 per cent of those who did not, the research, published in Annals of Oncology, found.
Each year around 15,400 people in the UK are diagnosed with malignant melanoma. Despite survival doubling in the last 40 years, around 2,500 Britons die from the disease every year.
Professor Richard Marais, director of the Cancer Research UK Manchester Institute, who led the research, said: "For some patients with advanced melanoma, their cancer will eventually return. We have no accurate tests to predict who these patients will be, so our findings are really encouraging.
"If we can use this tumour DNA test to accurately predict if cancer is going to come back, then it could help doctors decide which patients could benefit from new immunotherapies.
"These treatments can then reduce the risk of the cancer spreading. The next step is to run a trial where patients have regular blood tests after their initial treatment has finished in order to test this approach."
Professor Karen Vousden, chief scientist at Cancer Research UK, said: "Being able to develop an early warning system that will predict if a cancer will return could make a real difference to patients.
"Research like this shows that for some cancers, there may be ingenious solutions - such as a blood test."
Additional reporting by PA
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