The primary and secondary prevention of cancer.

Prevention of cancer is now divided into primary and secondary prevention. Primary prevention is that set of interventions that keeps a cancerous process from ever developing and includes health counseling and education, environmental controls. and product safety as examples. Secondary prevention is that set of interventions leading to the discovery and control of cancerous or precancerous processes while localized, i.e., screening, early detection, and effective treatment. Risk is lifelong for all, though it may vary in intensity among different groups. Jointly, primary and secondary prevention must be synthesized into optimum life time strategies that are best understood and evaluated under certain basic concepts of the epidemiology of cancer and operations research. The purpose of this report is to provide a brief review of these concepts applied to primary and secondary prevention of human cancer. Improved understanding of these concepts is essential for planning, implementation, and evaluation of prevention programs.