There are reportedly a number of different stories circulating wrt nature's preventative cures for cancer, a friend of mine told me something about the center of a particular fruit, I want to say apricots, not sure, and then I'd also heard about a particular spice or herb that's used in the east, some asian foods, mostly indian that prevents cancer.
Most of the examples they cite deal with tests on tribes or portions of the population where exposure to certain Western products is very low and exposure to the aforementioned items is highly concentrated. Interesting stuff.