Another tip: do the fast diet. Studies in the UK have proven that it's one of the best diets, especially for people who suffered cancer to prevent its recurrence. It's simple: two days of fasting (below 500 kcal for women or 600 for men) and five days of "normal" diet. It's supposed to make us get back to our original way of life when we didn't have plenty to eat each day.
RE: Key Changes in Your Lifestyle to Prevent Cancer