Thats a really hard question to answer really. We are working towards better treatment therapies and slowing the progression of them. For leukemia and Parkinsons there are new drugs being trialled all the time as they are targetted towards their causes.
But for cancers in general there are so many types and so many different causes that we need to target each persons cancer specifically and not effect the rest of their cells. This is called personalised medicine and is something we are trying to develop with new genetic technologies. We aren’t that far away, but still probably in the tens of years. It may well be something we see in our time if we are lucky 🙂
(Helen and Amy are our specialists and may argue with me there though :P)