Genetically controlled mechanisms cause tumors to start and spread; cancer drugs that target these mechanisms can deliver individual tumors a knockout blow. That’s where we’ve made the most progress.
There are over 200 different types of cells in the human body. There are three main types of skin cancer. There are four main types of lung cancer. I could go on. The name cancer s very misleading because you'r talking about hundreds of different diseases at a minimum.
Not to refute what you said, just can’t help thinking if we treat them as separate diseases, we run the risk of missing the forest for the trees.
First, we have different types of cancer according to where in the body it started, e.g., lung cancer, liver cancer. Then, depending on exactly where in the organ it started, e.g., on the lining or deep within, we have the finer types of cancers. These classifications do not preclude the possibility of a common pathogen behind them all.
And different types of cancers behaving differently should not be too surprising because cells belonging to different organs have different structures and physiology to begin with. A cancerous cell is apparently still able to bind to the various substances carried in the blood like it used to, though the effects of those substances are now changed.
Anyway, what do I know? Still, I am very hopeful a cure will be found.