A public health approach to winning the war against cancer.

The "war on cancer" in the United States has been viewed primarily as an effort to develop and disseminate cancer cures, but cancer is far more easily prevented than cured. There are three major approaches to cancer prevention: Primary prevention, through reduction in risk factors and changes to the environment that reduce human exposure to widely-consumed cancer-promoting agents. The most important actions for primary prevention of cancer are those that reduce tobacco use through taxation, smoke-free environment policies, advertising restrictions, counter-advertising, and cessation programs. The World Health Organization's MPOWER package outlines these actions, each of which covered less than 5% of people in the world in 2007. Similarly, cancer can be prevented by reducing alcohol consumption through policies such as alcohol taxes and limits on alcohol sales, and restoring caloric balance through policies such as creating healthier food environments and engineering the built environment to increase opportunities for physical activity. Vaccination is an effective approach to preventing specific virus-associated cancers, such as using human papillomavirus vaccine to prevent cervical cancer and hepatitis B virus vaccine to prevent hepatocellular cancer. Secondary prevention reduces cancer mortality through screening and early treatment; this approach has been used successfully for breast and cervical cancer but is still underused against colon cancer. Progress can be made in all three approaches to cancer prevention, but will require a greater emphasis on public health programs and public policy. Winning the war on cancer will require a much larger investment in prevention to complement efforts to improve treatment.