The Social Determinants of Cancer

Abstract

It is clear that social factors play a role in cancer incidence and mortality. Increased risk of cancer is associated with tobacco use, diet and alcohol, reduced physical activity, exposure to the sun and to environmental toxins. These relationships are relatively well established and quantified and there is broad understanding of their pathophysiological role in the etiology of cancer. All these factors are influenced by social, cultural, and environmental factors. The growing field of social epidemiology, however, is drawing attention to the role of more 'upstream' factors in health and disease [1]. Examples might include the influence of commercial marketing activities, relative social status, levels of income and education, access to the health care system system and the strength or absence of social networks. There is increasing evidence that such social level factors have an important etiologic role in cancer, but this role is far more difficult to study. This challenge has stimulated research that seeks to clarify the relationship of social factors and cancer and this issue of the journal presents two examples. In the first, Ocafia-Riola et al., studied the relationship between the incidence of cancers, socioeconomic levels and exposure to environmental toxins in defined geographic regions of Southern Spain [2]. They hypothesized that cancer may be associated with differential exposure to environmental toxins as reflected by areal measures. They found associations for most cancers with a measure of urbanization and for some cancer sites with measures of unemployment, illiteracy, and area under cultivation. Unfortunately, even though these association may suggest topics for further exploration, there seemed to be no commonality between the cancer sites associated with various factors. The authors did not offer any conjectures about biologic mechanisms. Jansson et al., in Sweden, looked at the possible impact of psychologically demanding work on the incidence of esophageal adenocarcinoma, squamouscell carcinoma, and adenocarcinoma of the gastric cardia [3]. They used data from individuals asked to recall conditions from 20-years earlier on job strain and work place satisfaction. The study demonstrated a modest relationship of new cases of these cancers with coping styles, not the job stress itself and a rather strong relationship with satisfaction regarding the pace of work. The authors speculate that the mechanism might be due either to the effect of inadequate coping with psychological stress on relaxing lower esophageal sphincter pressure, or perhaps to impaired immune function. The results of these two studies are of interest independently, but also illustrate the need for a broader approach if epidemiologists hope to elucidate the role of social determinants of cancer. Far more detailed