It is a valuable process for a multi-cellular organism to allow cancerous cells to kill themselves.
Those cancers that have a p53 mutation are not subject to this process of p53 induced apoptosis.
Thus the of the cancers that grow and survive within the body long enough to be detected; around 50% have already shut off the mechanism whereby the cell would be instructed to kill itself.
K.
You're still describing the effect, not the cause.
Now instruct us (who are less likely to die from cancer) about the WHY question I asked. Why is p53 mutating and allowing cancerous cells to propagate?
It's easy to point to a breakdown in the defenses, but why are the defense mechanisms of the immune system breaking down in the first place and allowing the cancerous cells to live?
If you have the answer to that, you should stop wasting your time lecturing noobs on a political board and get down to the CDC with your findings!