The stages of cancer do not classify cancers according to how aggressive they are (though, naturally, more aggressive cancers are more likely to be diagnosed at later stages). They just tell you how far the cancer has already spread. Any cancer, rightly so called, has already accumulated enough mutations to be capable of metastasizing, including mutations that greatly accelerate the rate of mutation. Once you have cancer, there's generally not much point in trying to slow down the process of developing cancer.

The link between diet and cancer risk is only supported for certain cancers, and is generally not as strong as I think people imagine--even for colon cancer, the effect of diet is nowhere near as strong as the effect of smoking on lung cancer risk, for example.

Even so, I upvoted your first comment, for being the only one here to point out that Jobs had a pretty indolent cancer, and that nine months' delay may or may not have made a difference to his outcome. There was a decent treatment of the question at Science-Based Medicine this week.