Racial, ethnic, and gender variations in cancer risk: considerations for future epidemiologic research.

There is no question that the risk of many cancers varies substantially by race, ethnic group, and gender. Although important clues to cancer etiology may come from investigating the differences in risk across subgroups of the population, epidemiologic research has often focused on white men. More descriptive and analytic studies are needed to identify and explain variations in risk among population subgroups. Especially important are studies to clarify the role of differential exposures, susceptibility, and diagnostic factors in cancer incidence, although differences in treatment may contribute to variations in cancer mortality. Improvements in classification of ethnicity, assessment of carcinogenic exposures in various subpopulations, and measures of host susceptibility states should augment future epidemiologic research designed to better understand mechanisms underlying the racial, ethnic, and gender differences in cancer risk.