From what I have read, very low carb diets have been shown to slow and shrink
tumor growths.  I have also read that cancer feeds off glucose so a
sugar-free low carb diet makes sense.

Since time is of the essence, I believe that other measures in addition to
diet are in order.  If possible, I would immediately try to find a reputable
alternative doctor.  I would contact the Atkins Center in NYC (Dr. Atkins is
extremely knowledgeable about alternative cancer therapies) and ask for a
referral or contact FAIM (Foundation for the Advancement of Integrative
Medicine -- go to faim.org -- and ask for a referral.