When people are diagnosed with a cancer many questions come up, among them what might have led to the development of cancer, especially with regard to behaviors the person adopted that increased their risk for the disease. Otis Brawley, a cancer epidemiology expert at Johns Hopkins, says studies can be a bit confusing.
Brawley: When we get to cancer everybody wants to know why it happened or why this poor person got it and then the truth is in 58% of all cancers we have no idea why the individual got it. We actually refer to it in science as bad luck and having a bad luck mutation. We frequently do studies that give us correlation but that doesn't necessarily mean causation.  :27
Brawley says confusion over correlation and causation may motivate people to engage in some things and avoid others. If the goal is to reduce the risk of cancer it’s important to look for those studies that show causation, such as cigarette smoke and lung cancer. At Johns Hopkins, I’m Elizabeth Tracey.