Cancer epidemiology in the United States: racial, social, and economic factors.

It is widely accepted that there is a differential burden of cancer in certain populations, including racial/ ethnic minorities, the medically underserved, and older adults. Differences in survival, stage at diagnosis, and risk of death have been identified in these populations for cancers of the lung, colon and rectum, prostate, and female breast. The factors that drive these disparities are not uniformly understood. Addressing the unique issue of racial differences in cancer epidemiology necessitates a discussion of the definitions of "race" and "ethniCity," and an analysis of the validity of these concepts within the context of scientific study. Poor cancer-related health outcomes in groups of low socioeconomic status highlight issues of access to care and preventive care use. There is a scant amount of data on cancer in the elderly, and the special considerations that this group faces. A unique challenge facing cancer epidemiologists is suboptimal recruitment of members of these groups into clinical studies, which precludes a robust understanding of the existing disparities. It is critical to appreciate the overlap that exists between these populations, because this may complicate data interpretation. Legislative efforts that have, in part, been driven by the National Center on Minority Health and Health Disparities and by the Department of Health and Human Services, will continue to play an instrumental role in the identification and resolution of cancer disparities in these groups.