All living creatures must eat. Cows eat hay, teenagers eat potato chips, and tumors need blood. The bigger the tumor, the more blood vessels it must grow to feed itself. Researchers are examining ways to slow or stop the growth of blood vessels.
Research is new.
These tumors actually have receptors for this medication. That is the idea behind radioisotopes. In this manner, you target the tumors. This is a VERY new field, with one study under way, and another about to begin. One top researcher doubts ANY such connection for midgut or hindgut tumors.