You can help prevent cancer from happening by making sure your body's pH levels are more basic than acidic (cancer cells don't easily thrive in base-pH'd bodies) - you can do this by living a very healthy and active lifestyle (eat well and sleep well, exercise, drink plenty of water, get plenty of sunlight, etc.), consuming certain health-foods that promote a basic body-pH, and regularly cleansing your body of any accumulated toxins via various detoxes. There's much more to it than this (feel free to research this to your heart's content), but these things alone can give you a really good start :>