I think they can't cure it because current treatment is to kill the daughter cells and not the mother cells. Cancer happens when stem cells have a genetic mutation. These are the mother cells and they crank out babies like mad. These babies forget how to perform apoptosis (programs cell death which is present in all normal cells). That makes the stem cells and tumor cell immortal and they just go on and on reproducing and making more cells which is the tumor.
We need treatments that eliminate the defective stem cells - hopefully by turning on the immune system to recognize these cells as abnormal and kill them without side effects. Once we get rid of the stem cells then, and only then, will cancer truly be curable.
take GOoD care