As many unsuccessful stories as you can turn up, I can turn up just as many success stories on GT. How helpful the coffee enemas are, is still up for debate in my opinion.
Cancer just so happens to be one of those diseases that is quite possibly the result of a continuous assault on the body through poor diet.
For instance, in one study, researchers were able to literally turn cancer on when mice were given casein (a protein in milk) and off with its removal.
I would question how do you know that a poor diet is not the cause of the disease. In my belief, it is not the food that heals, but it is the body that does so when provided the tools (nutrition) to do so.