Hundreds of patients with a type of aggressive skin cancer will be offered a targeted therapy on the NHS in England and Wales, which reduces the risk of it returning.
At present, they have to hope their cancer will not return after surgery.
The drug has been shown to improve the survival of people with stage III melanoma, with a particular mutation.
A skin cancer charity said making the treatment available on the NHS was “a huge step forward”.
Melanoma is the most aggressive type of skin cancer, with 15,400 new cases diagnosed each year in the UK.
A gene mutation called BRAF is found in approximately half of cases – and around 500 of those people have stage III.
This means that cancer cells have spread into skin, lymph vessels or lymph glands close to the melanoma, but they haven’t spread to more distant parts of the body.
Increase in survival
The therapy, which has been approved by the health body NICE – the National Institute for Health and Care Excellence – is a combination of the drugs dabrafenib and trametinib which can be taken at home as five tablets a day.
It comes after a clinical trial of more than 800 patients found a lower risk of the cancer recurring in a group taking the therapy.
Three years after surgery, 58% of this group survived with no relapse compared to 39% of the placebo group.
The therapy was also found to increase the overall length of time people live, by reducing how many people develop an incurable form of the disease.
However there were side effects, including fatigue and nausea, that occurred in a third of patients taking the therapy, and 10% of the placebo group.
Gill Nuttall, from charity Melanoma UK, said: “We are continuing to see an increase in the number of people in the UK with melanoma, especially among younger people.
“The availability of this treatment is a huge step forward for the hundreds of BRAF-positive patients who are currently left with very few options following surgery.
“The current ‘watch and wait’ approach is an extremely worrying and stressful time for patients and their families.”
Melanoma accounts for more deaths than all other skin cancers, with around 2,400 in the UK every year.
Mirella Marlow, deputy director for the NICE Centre for Health Technology Evaluation, said there were currently no treatments available for people with this stage and type of melanoma to lower the risk of the cancer coming back.
She said the decision marked “an important development in the management of melanoma”.
Professor Ruth Plummer, clinical professor of experimental cancer medicine, University of Newcastle Upon Tyne, said the treatment had “the potential to transform the standard of care for people with BRAF-positive stage III melanoma”.