I believe that the most critical item to address is balancing the pH.
Several ways have been mentioned to do this. A diet of all raw fresh fruits and vegetable (juicing is great) helps to do this and has many other additional benefits.
Second, I think is providing a diet full of antioxidants. The raw uncooked fresh fruits and vegetables help with this.
Third, and I am sure that I might receive a bit of flak from any traditional oncologist, but limit sugars, especially refined sugars.
Otherwise, I have heard of excellent results from followers of Dr. Clark, drinking Essiac Tea, taking PawPaw extract, and taking Hydrazine sulfate.