[ndt]

"Thus the cancer cell is a failed mutation?"

It depends on your definition of failed. In the case of "Devil Facial Tumour disease", the cancer has actually mutated into a self replicating contagion which is a pretty darn successful mutation, for the cancer anyway, not so much for the devils.

[ahayes]

Great minds, etc. etc. ;-)

[RobbyS]

Looking from the viewpoint of a human rather than a cancer, I do see a certain failure here. It is not as though this change is potentially better such as the development of thick bodily furr for use in a northern climate.