Scientists study patterns of cancer in the population to look for factors that affect the risk of developing this disease. In the laboratory, they explore possible causes of cancer and try to determine what actually happens when normal cells become cancerous. Our current understanding of the causes of cancer is incomplete, but it is clear that cancer is not caused by an injury, such as a bump or bruise. Cancer develops gradually as a result of a complex mix of factors related to environment, lifestyle, and heredity. Scientists have identified many risk factors that increase the chance of getting cancer.
Some people are more sensitive than others to factors that can cause cancer.
Many risk factors can be avoided. Others, such as inherited risk factors, are unavoidable. People at risk can help protect themselves by avoiding risk factors where possible and by getting regular checkups so that, if cancer develops, it is likely to be found early. Tobacco causes cancer. Tobacco use is the most preventable cause of death in this country.