Epidemiology: a step forward in the scientific approach to preventing cancer through chemoprevention.

Until quite recently, the rigor and systematic approach applied to clinical research had never been applied to cancer prevention research. During 1982-83, however, the National Cancer Institute (NCI) carefully reviewed the needs and potentials in cancer prevention and control and developed a new policy for prevention research, requiring that development of cancer intervention follow an orderly sequence of research phases. These phases provide systematic assessment of interventions so that only those proven to be effective are brought to widespread implementation. The author presents an overview of the new cancer prevention research policy; explains the manner in which epidemiologic studies contribute to development of policy and research; and describes NCI's research plan for chemoprevention, providing highlights of research studies that have contributed to its development and that will be implemented under the plan.