As simple as this headline claims, then most of us who have cancer wouldn't. Or if we did, we could somehow "get better" short of chemo, etc.
I support healthy eating, living and exercise. I do it, for the most part. Always have, always will. Didn't stop me from getting breast cancer at 37.5 years old. Doesn't stop a whole bunch of other people from getting diseases either.
The message to do your best for yourself where your health is concerned is good. The undertone that we who are unlucky enough to get sick big are at fault is not.