Primary prevention of cancer: needs and opportunities for research.

Strategies for cancer prevention generally come from observational epidemiology and must include monitoring for the effects of the actions. The measurement-iterative loop allows us to refine our approach to cancer prevention. When available, clinical trials can also provide strategies for control. Exposure-specific strategies are described; these are such things as health promotion and behavior modification, legislative approaches, treatment for addiction, changes in the food supply, chemoprevention, occupational and environmental regulation, immunization, identification of persons with enhanced genetic susceptibility, and improved surveillance systems. For some exposures such as tobacco, zero exposure is the goal. For others, prudent avoidance or exposures as low as reasonably achievable are appropriate approaches. Research on how to impact deeply ingrained lifestyle and cultural factors has high priority.