How long does it take for skin cancer to kill someone if left untreated?

They would likely show no symptoms other than the cancer on the skin until it was too late to do anything. Skin cancer can remain on your skin with no complications for an indeffinite amount of time, possibly years BUT when the thing breaks and spreads it spreads like wild fire through out the body effecting the blood, lymph nodes and everything in between. The patient could be dead in months depending on where the cancer traveled. My cousins wife died this way, she began treatment but she didn’t discover it early enough so she died at 30 yrs of age after 6 months of treatment.On the other hand, my younger brother was sitting on the sofa when I noticed a misshapen mole on his back (black), I asked how long he had it and he said a couple of years. I told him it was a melanoma and he needed to get it removed, he didn’t believe me but after pushing him for 3 months he went in, it was cancer but had not ruptured or spread so now 10 yrs later he is still cancer free.