Do not smoke, avoid exposure to sunlight, sleep well, drink water, exercise.

It’s challenging and controversial because of the limitations of causation. We can often times prove correlation between environmental factors and cancer. Like discovering a cancer cluster in a population of people that live next to some kind of industrial plant. It may seem obvious that the cancer in this group of people is being caused by ground contaminants from the industrial plant these people live next to. But just because you can prove correlation dos not mean you can prove causation. The biological links between cancer manifestation and contaminants is still poorly understood and when trying to prove culpability this correlation versus causation argument gets very complicated.