Very serious. Melanoma's response to 21st century treatment is so unpredictable that even lung metastases, which until recently did mean certain death eventually, might perhaps be compatible with long-term survival.
Varies. This depends if the metastatic disease can be removed surgically. The best chance at survival depends on removal of all the disease.
Now more treatable. If there is a single mass or perhaps 2 surgery or radio surgery might be possible. There are 2 new treatments that could be helpful. One attacks a braf mutation. It can have dramatic results if the tumor is sensitive, but duration is short. Another new drug.Puts the immune system in advanced overdrive and has benefit for a much longer time. Still, unfortunately not curable.