[pohl]

The concept you want to understand is metastasis. When a cancer metastasizes, it sends out cells that become cancers elsewhere in your body. One day just just have a little melanoma, the next day it sounds out cells that become cancers in other organs: your lungs, your liver, etc.

Some skin cancers, like basal cell carcinoma, never metastasize. Melanoma is one that will.

https://en.wikipedia.org/wiki/Metastasis

[pas]

Think of metastasis as, that particular cancer evolving to a level where it can successfully break through the "impedance mismatch" of colonizing other tissue.

At that point it's more like multiple cancers at the same time, with the very cruel consequences of exactly how drastic that sounds :/