Relative Value of Incidence and Mortality Data in Cancer Research

Abstract

Epidemiology, the scientific study of the distribution and determinants of disease in man, is playing and will continue to play a central role in the war against cancer. The special role for data relating to cancer in assisting our understanding of the nature of the causes of cancer is well acknowledged. Fundamental in formulating the hypothesis that cancer is environmental in origin have been cancer occurrence data from different populations, from migrant groups and from special groups such as the Seventh Day Adventists and Mormons whose life-style distinguishes them from other members of the same community. It has been descriptive epidemiology, rather than analytical epidemiology, which has given rise to most hope for preventing cancer, the aim of every form of epidemiological study (Clemmesen 1965). It is believed that most forms of cancer are preventable, for most preventable causes have yet to be identified with any degree of certainty for a significant proportion of cases, even though epidemiological studies have afforded varying degrees of insight into the aetiological factors responsible for cancers of certain sites. While we know, for example, of a variety of risk factors associated with breast cancer (Kelsey 1979; Boyle 1988), it remains unclear as to the avoidance of which factors would best reduce the incidence of this important form of cancer. On the other hand, a sizable majority of lung cancer, perhaps over 85%, could be avoided by elimination of cigarette smoking (U. S. Surgeon General 1979, 1982).