Although there's a lot we don't know about what causes cancer, there is enough we do know that gives us steps we can take to help prevent some forms of it.
Doctors believe that a lot of cancers have some genetic link.
There's not much you can do about your genes. There are other risk factors, though, that are relatively easy to control. The biggest is probably smoking. About a third of all cancer deaths each year have something to do with tobacco use. Secondhand smoke appears to carry some risk, so offices and other places that maintain smoke-free environments are helping keep people healthier.