When you eat raw food, the body accepts it and uses it efficiently. We have only being cooking food a few thousand years, and this is not very long on the evolutionary time scale, so the body has not had enough time to adapt to this change. That includes the sudden change of our lifestyles. As a consequence to this rapid change in diet and lifestyle, we get sick. Our immune system is what keeps us healthy, so by knocking it down with poisons such as sugar and cooked food, amongst many other poisons in our diet, we are likely to get ill.
Cancer occurs if the immune system has been compromised.
The body produces millions of cells all the time, and it makes errors every so often. One of the tasks for our immune system is to clean up those errors, and normally it does so effectively. If, however, the immune system has been knocked down, it can't do this effectively, and the errors grow and grow and that is how the cancer develops. Aquired Immune Deficiency Syndrome. The clue to the cure is in the name.