Ray,

There was some pioneering work done along those lines: starving the tumor by cutting off the blood flow. The scientific name for this process is called anti-angiogenesis, or, the blocking of new blood vessel creation. The doctor who pioneered this theory work won a Nobel Prize, I believe. The sad thing is, the idea never really worked well in clinical practice.

There is a new idea that is taking root in the scientific community regarding the treatment of cancer. Instead of finding a "cure", which most believe will not happen in our lifetimes, they should focus on finding cancer in the early stages where it's most treatable. There is some interesting work, as Brian mentioned earlier, that is going on with that.