Good information and a very thoughtful reply. Thanks!
I would point out one item, though. It is not "the body" per se that is providing new blood vessels voluntarily for the tumor to keep it alive - it is the tumor caused process of angiogenesis which is causing the body to create the blood vessels in an attempt to keep the tumors alive and growing. Once again, I see that as a cancer survival mechanism and not as any overall body mechanism of trying to stay alive.
The bottom line to me is that cancer is a condition that will often kill you if left untreated, so in that sense it is a very poor process of trying to keep the host itself alive. Perhaps it would be better said that cancer is a very effective and loud signal to the body that it needs to correct the conditions that led to cancer in order to survive.