The government does not choose the metrics; the scientists who are working the problem do that. Tumor shrinkage is a direct result of cytotoxicity against the cancer cells--as the cancer cells die, the tumor shrinks. So, for a researcher looking to kill off the cancer, that is a pretty good indicator that the treatment is effective.
The development of resistance to the cancer drugs is pretty much an unavoidable consequence of treatment. It is analogous to bacterial resistance to antibiotics. Cancer cells within a tumor are not genetically identical, so some are less affected by the cancer drug than others. So, if the drug does not kill *all* of the cancer cells, the ones that survive and grow are the ones that were already somewhat resistant to the drug.
The government insisted on a molecular biological approach and only funded those efforts. Alternative approaches like treatments that prevented the growth of feeder arteries and veins were not investigated until recently. Some scientists urged treating symptoms rather than trying to kill the underlying mechanism as that is a moving target. They didn’t get government funding and the government is the only game. Survival rates for some cancers hasn’t changed since the ‘50’s, which would argue for a different approach.
Since cancer is a disease of disregulation of cell growth, which occurs at the molecular level, the molecular biology approach towards understanding cancer is completely appropriate. What you call "alternative approaches" are actually molecular biology approaches that were not even possible ten or twenty years ago, because the underlying molecular mechanisms were not known yet. And those mechanisms are known now because of research in the field of toxicology, not cancer. Since we still (after decades of research) do not know exactly how dioxin kills, researchers were looking for clues. As a result, they discovered a previously unknown component of the toxic response system that controls angiogenesis (growth of blood vessels). Once that component was discovered, it did not take long for other scientists to show that the same component is responsible for blood vessel growth in tumors. So, with the discovery of this new molecular target for therapy, other scientist started developing new drugs, some of which are being tested clinically for cancer treatment. This research, like most research, is funded by a variety of government and private sources.
Treating symptoms is fine for patient care, in that it makes the patient more comfortable. But it does nothing to cure the underlying problem. Still, scientists looking to treat symptoms also get funding. Keep in mind, it is not the government that decides how the funds are disbursed, but rather committees of scientists, mostly from academia. They decide whether projects are funded, based on whether they think the project has scientific merit.
I don’t accuse scientists of getting rich. But when I worked at a college lab they viewed grants as their job, not finding solutions. I’m sure there are dedicated scientists. But they must share funding with hacks who simply like university life.
Without grants, a university scientist cannot perform his/her work. It is an unfortunate fact of life that university scientists end up spending a disproportionate amount of their time writing up grant proposals and sitting on grant review committees. Even as a post-doc student, I read and judged grant proposals. The biggest complaint from university professors is that they do not have time to go into the lab and work at the bench--the very work that they became scientists to do. I think I can count on one hand the number of times I actually saw my mentor doing bench work in the lab. I've seen what university life looks like, and chose to do something else with my education. While I would love to teach, I hate the baggage that comes with it.
Thank you both for that instructive exchange.