Cancer Research UK scientists have discovered that testing skin cancer patients’ blood for tumor DNA could help predict the chances of an aggressive cancer returning.

Published in the Annals of Oncology, the findings could pave the way to identifying patients who are most at risk of their disease returning, and who might benefit from new immunotherapy treatments.

Led by researchers based at the Cancer Research UK Manchester Institute and The Christie NHS Foundation Trust, scientists studied blood samples taken after surgery from 161 patients with stage 2 and 3 melanoma. They then looked for faults in two genes that are linked to 70% of melanoma skin cancers—BRAF and NRAS.

After 5 years, 33% of patients who had a positive blood test for faults in either of the two genes were alive, compared to 65% of those who did not.

The results also revealed that skin cancer was much more likely to return within a year of surgery in patients who had faults in either of the two genes.

Each year around 15,400 people in the UK are diagnosed with malignant melanoma. And while survival has doubled in the last 40 years, around 2,500 people die from the disease every year in the UK.

Professor Richard Marais, lead researcher and director of the Cancer Research UK Manchester Institute, based at the University of Manchester, 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 tumor 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, Cancer Research UK’s chief scientist, 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. If follow-up research shows that this test can be used to inform treatment decisions and improve outlook, it could be a game-changer in our ability to deal with advanced skin cancer.”