Chemicals and other risk factors cause genetic damage which, in turn, results in cancer. Over time scientists have learned a great deal about cancer, it's causes, and early detection. Prevention is about applying this understanding to reduce cancer risk. For example, tobacco use is responsible for more than 30 percent of all cancers and 90 percent of lung cancers. Anything that increases a person's chance of getting a disease, such as cancer, is referred to as a risk factor.
Smoking is the primary risk factor for lung cancer.
Sunburns are a risk factor for skin cancer. In these examples, smoke and sun exposure are the specific factors increasing the likelihood of getting caner. Repeated exposure to a risk factor does not necessarily mean that you will get the disease, but it does mean that the possiblilty that you may get cancer is increased. Prevention focuses on those things in your life you can control. Minimizing your exposure to tobacco smoke and the sun's rays will reduce your risk of certain cancers.