Epidemiology of Cancer - Risk Factors

Risk Factors

The most significant risk factor is age. According to cancer researcher Robert A. Weinberg, "If we lived long enough, sooner or later we all would get cancer." Essentially all of the increase in cancer rates between prehistoric times and people who died in England between 1901 and 1905 is due to increased lifespans. Since then, some other factors, especially the increased use of tobacco, have further raised the rates.

Over a third of cancer deaths worldwide are due to potentially modifiable risk factors. The leading modifiable risk factors worldwide are:

• tobacco smoking, which is strongly associated with lung cancer, mouth, and throat cancer;
• drinking alcohol, which is associated with a small increase in oral, esophageal, breast, liver and other cancers;
• a diet low in fruit and vegetables,
• physical inactivity, which is associated with increased risk of colon, breast, and possibly other cancers
• obesity, which is associated with colon, breast, endometrial, and possibly other cancers
• sexual transmission of human papillomavirus, which causes cervical cancer and some forms of anal cancer.

Men with cancer are twice as likely as women to have a modifiable risk factor for their disease.

Other lifestyle and environmental factors known to affect cancer risk (either beneficially or detrimentally) include the use of exogenous hormones (e.g., hormone replacement therapy causes breast cancer), exposure to ionizing radiation and ultraviolet radiation, and certain occupational and chemical exposures.

Every year, at least 200,000 people die worldwide from cancer related to their workplace. Millions of workers run the risk of developing cancers such as pleural and peritoneal mesothelioma from inhaling asbestos fibers, or leukemia from exposure to benzene at their workplaces. Currently, most cancer deaths caused by occupational risk factors occur in the developed world. It is estimated that approximately 20,000 cancer deaths and 40,000 new cases of cancer each year in the U.S. are attributable to occupation.