Cancer is considered a progressive multi-step disease, why is this?
Tumor development arises from the accumulation of 4-6 different mutations in cells over the course of many years.
Tumors development spreads to other tissue with time.
Tumor development requires mutations in the affected cells, as well as defects in the immune system.
Tumor development happens in a step-wise fashion as telomeres shorten with each cell division.
Tumor development gets worse with time.
