Two drugs taken together can shrink tumours in nearly 60% of people with advanced melanoma, scientists have suggested.
In a trial of 945 patients using ipilimumab and nivolumab the cancer was stopped from developing for nearly a year in 58% of people.
Scientists said the drugs work by alerting the body's immune system to the cancer and allowing it to fight off the disease.
It's still unknown how long the drug can prolong life or if it has any side effects several years later.
Initial side effects can include fatigue, a rash or diarrhoea.
The study also found that a number of patients had no response to the treatment at all.
Steve Fouch from the CMF gave it a cautious welcome on Premier's News Hour.
He said: "This study is still in its fairly early stages, we don't know how much longer it's actually helping people to live for starters. We know that it causes a shrinkage of tumours and it's certainly having an impact in terms of the health and wellbeing of people.
"It's often very easy to get one study and everyone gets hyped up and excited about it, but you need to actually repeat these results with other groups to actually have some kind of an idea whether this is effective and relatively safe. As I said, we still don't know about the long-term side effects.
"The likelihood is that if this treatment ever does become fully approved, and it may well do if further research is positive, it will only ever be for people in the most extreme circumstances and it will only ever be in a limited number of those people who are likely to respond positively to it.
"We're talking probably it may be adding months or a year or so to life. Now that's worth having, I think, but it's not a cure."