Playing devils advocate:
-Steve Jobs was diagnosed with pancreatic cancer 20 years before he died. The average life expectancy for that type of cancer at his time of diagnosis was 3-6 months. That is rare - REALLY rare. He was doing something right. He was never doing chemo or traditional treatment - yet he outlived the average life expectancy by 40x conservatively.
Where did you find the info that he was diagnosed 20 years ago.
All I can find that first diagnosis happened in 2003, which is 10 years ago.
Living with cancer for 20 years, relaying mostly on dieting choices (from what we know) would be quite a feet and proof that dieting does affect cancer's spread a lot.