Cancer and food you eat is related, but if you ask Oncologist they will say you that reasons that some people have cancer are this:
33% Food (what you eat, best food for 0% in this area is Vegan food) 33% style of life (stress, sleeping, smoking, drinking...) 33% Environmental (radiaton, bad air, smog, chemicals....)
So as you see if you eat vegan food it does not mean you will never have cancer, if you do all other factors you will still have high 66% to get one, now do the math if you eat meat and do all the rest, hehe
Steve Jobs was a business man so his style of life was probably not at 0% free from cancer and even if he had 10% chance + some environmental factors, maybe smog, bad air and here it is at 20% and that is not small %.
In other words, if you live in big dirty city you could have already 15% chance to get cancer.
This percents are noz correct, i put them so you get a idea how things work.