Phase 4: Defined population studies. The impact of an efficacious intervention is measured when carried out in a large, well-characterized population representative of the ultimate target group.
Phase 5: Demonstration and implementation studies. The intervention that is proved to be effective and generalizable in the previous research phases is applied to a community at large. The public health impact in terms of reductions of smoking incidence and prevalence and ultimately cancer incidence, morbidity, and mortality is measured as the intervention is systematically applied to the broader target population.

In the years 1984 to 1989, the emphasis in the STCP is in phases 3 and 4 to determine the most effective strategies for reducing smoking incidence and prevalence. By 1990, the NCI will be prepared to enter phase 5, demonstration and implementation studies, and thereby have a solid decade for the dissemination and diffusion of those strategies proved to be effective. The results of this decade of demonstration activities should yield a marked reduction in smoking prevalence and thereby contribute to a reduction of the attendant smoking-related cancers. (Fig 4). comments

Conclusion
Unlike the days following the 1964 report of the Surgeon General on the health consequences of smoking, the NCI’s emphasis is no longer on the definition of the problem and the accumulation of evidence linking smoking and tobacco use to cancer. The emphasis now is on reducing the prevalence of tobacco use throughout the US. The cancer control objectives for the nation now specify that we need to reduce the percentage of adults who smoke from the 34% rates found in 1983 to 15% or less by the year 2000, and reduce the percentage of youths who smoke by age 20 from 36% characteristic in 1983 also to 15% or less. By doing so, the NCI will contribute to the continued gain in reduced incidence of cancer.
The trend of success is in our favor. The tide of public opinion is on the side of those who have been vigilant in their applications of whatever knowledge and science has been available to bring smoking and tobacco use prevalence down. But the challenge still exists. The numbers of individuals who apply themselves to the challenge and the resources required have to be maintained and perhaps even increased if these objectives are to be obtained. It is the intent of the NCI to play a very visible and assertive role in this effort.

Figure 4

Figure 4