Comment Re:Cancer just doesn't have that "it" factor!! (Score 1) 96
Ultimately, it is the immune system that keeps your body free of cancer. Cancers happen frequently in your body, and the immune system beats them down. When it fails at that for some reason, only then does clinical disease happen.
You could make the same argument about MANY functions within your body. There are many different mechanisms in cells that work to prevent uncontrolled cell growth. There are many controls on the cell cycle which have to fail. The tumor needs to create demand for more blood vessels to sustain growth. The tumor has to evade the immune system, etc.
It seems like cancer is the flip-side of multicellular life, and as a result humans have many different mechanisms for preventing it. Only when they all fail do cancers form. The problem is that you have billions of cells independently dividing and every time they do there is an opportunity for more mutations to creep in. Sooner or later any level of redundancy is bound to fail.