SOURCE: PhotoDisc, Inc.

public health efforts. The future rates of cancer were calculated by the following formula: (1990 population attributable risk2) × (projected reduction after the period of latency in the prevalence of the risk factor). The total reduction in cancer incidence and mortality rates was calculated as a weighted average of the rates of cancer of the lung, other tobacco-related sites, colon-rectum, breast, prostate, and other sites.

Byers and colleagues found that past and future reductions in rates of tobacco use were the single largest contributor to the projected future declines in overall cancer incidence and mortality rates. Other risk factors for which declines in prevalence were projected to be important contributors to declines in cancer incidence and mortality rates were poor dietary practices (low levels of consumption of fruits and vegetables), especially for colorectal and lung cancers; levels of alcohol intake; and failure to be screened, especially for colorectal cancer and, to a lesser extent, breast and prostate cancer.

Byers and colleagues estimated that if the reductions in the prevalence of risk factors continued at the 1990 rate, the total reduction in the cancer incidence rate would be 13 percent from 1990 to 2015 and the reduction in the cancer mortality rate would be 21 percent from 1990 to 2015. If the declines in the prevalence of these risk factors accelerated, however, the cancer incidence rate could decline by 19 percent and the cancer mortality rate could decline by 29 percent. When specific cancers are considered, some of the projections based on accelerated declines in risk factor prevalence were


The population attributable risk is the proportion of all cancers in the population due to a particular risk factor. Its calculation is derived from estimates of the relative risk for each risk factor (the ratio of the cancer incidence rate among those exposed to a risk factor divided by the rate among those not exposed) and the proportion of the population exposed to that risk factor (Byers et al., 1999).

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