Melanoma seems to have found its match in immunotherapy, a type of treatment designed to help the immune system fight cancer. Just a decade ago, only one-in-20 patients would live for five years after being diagnosed with late-stage melanoma, with most dying in months. But drugs designed to trigger the body’s immune system mean 52 percent of patients now live for at least five years, according to a new clinical trial.

Patients with melanoma, which is the fifth most common cancer in the UK, can be cured if the cancer is caught in its early stages, but as cancer spreads throughout the body, then survival plummets. With immunotherapy, however, researchers have found that tumors are reduced in size and stunted from growing any bigger.

Are these patients cured? Saying cured is always difficult in cancer, but five-year-survival is a hugely significant milestone. Some patients taking the drugs are in total remission with no sign of any abnormality on scans. Others still have a tumor inside their bodies, but it is no longer growing. Out of the patients that survived, three-quarters no longer need any form of cancer treatment.

The study shows just powerful immunotherapy can be in fighting cancers that were once deemed untreatable.