The Inside Matters: Random Gene Changes
Of course, environmental exposures by themselves do not cause cancer. Cancer is complex and involves many gene-gene interactions that occur inside you and are not well understood. For example, certain randomly occurring gene changes may be accumulating in your body's cells right now. And these same kinds of changes may not be occurring in your friends, your coworkers, or even your family members, even though all of you remain in a similar environment most of the time. Over your lifetime, random gene changes are passed along as your body cells grow and divide, so they accumulate. The unique patterns that evolve over time may make some people more likely than others to increase their risk for cancer after exposure to a particular chemical or after choosing a particular behavior.